Glossary
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- A -

abdomen - the area between the diaphragm and the pelvis

abdominal cavity - superior portion of the abdominopelvic cavity that contains the stomach, spleen, liver, gallbladder, pancreas, small intestine, and most of the large intestine

abdominopelvic - inferior component of the ventral body cavity that is subdivided into an upper abdominal cavity and a lower pelvic cavity

abduction - movement away from the axis or midline of the body or one of its parts

abortion - premature loss (spontaneous) or removal (induced) of an embryo or non-viable fetus; any failure in the normal process of developing or maturing

abrasion - a portion of skin that has been scraped away

abscess - a localized collection of pus and liquefied tissue in a cavity

absorption - the taking up of liquids by solids or of gases by solids or liquids; intake of fluids or other substances by cells of the skin or mucous membranes; the passage of digested foods from the gastrointestinal tract into blood or lymph

accommodation - a change in the curvature of the eye lens to adjust for vision at various distances; focusing

accretion - a mass of material that has accumulated in a space or cavity; the adhesion of parts

acetabulum - the rounded cavity on the external surface of the coxal (hip) bone that receives the head of the femur

acetylcholine - a neurotransmitter, liberated at synapses in the central and peripheral nervous systems and at neuromuscular junctions to stimulate muscle contraction

achlorhydria - absence of hydrochloric acid in the gastric juice

acidosis - a condition in which blood pH ranges from 7.35 to 6.80 or lower

acinar - flask like

acini - masses of cells in the pancreas that secrete digestive enzymes

acoustic - pertaining to sound or the sense of hearing

acromegaly - condition caused by hyper-secretion of human growth hormone (hGH) during adulthood; characterized by thickened bones & enlargement of other tissues

acrosome - a dense granule in the head of the spermatozoon; contains enzymes that facilitate the penetration of a spermatozoon into a secondary oocyte

actin - the contractile protein that is located in the thin myofilaments of a muscle fiber (cell)

acuity - clearness or sharpness, usually of vision

acupuncture - the insertion of a needle into a tissue for the purpose of drawing fluid or relieving pain; also an ancient Chinese practice employed to cure illnesses by inserting needles into specific locations of the skin

adaptation - adjustment of the pupil of the eye to light variations; the property by which a neuron relays a decreased frequency of action potentials from a stimulus of constant size; decrease in perception of sensation with continued stimulation

adduction - movement toward the axis or midline of the body or one of its parts

adenohypophysis - the anterior portion of the pituitary gland

adenoids - the pharyngeal tonsils

adenosine triphosphate - universal energy-carrying molecule manufactured in all living cells as a means of capturing and storing energy; it consists of the purine base adenine, the sugar ribose & 3 linearly-arrayed phosphate groups

adenylate cyclase - the enzyme that converts ATP into cyclic AMP; it is located in cell membranes and is activated when messenger molecules (e.g., neurotransmitters or hormones) bind to specific molecular receptors on the cell surface

adherence - firm contact between the plasma membrane of a phagocyte and an antigen or other foreign substance

adhesion - abnormal joining of parts to each other

adipocyte - fat cell; derived from a fibroblast

adrenal cortex - the outer portion of an adrenal gland; divided into three zones, each of which has a different cellular arrangement and secretes different hormones

adrenal medulla - inner portion of an adrenal gland; consists of cells that secrete epinephrine and norepinephrine in response to stimulation of preganglionic sympathetic neurons

adrenergic fiber - a nerve fiber that when stimulated releases norepinephrine (noradrenaline) at a synapse

adrenocorticotropic hormone - hormone produced by the adenohypophysis (anterior lobe) of the pituitary gland; influences the production & secretion of certain hormones of the adrenal cortex

adventitia - the outermost covering of a structure or organ

afferent arteriole - blood vessel of a kidney (nephron) that subdivides into a capillary network called the glomerulus; there is one afferent arteriole for each glomerulus

agglutination - clumping of microorganisms or blood corpuscles; typically an antigen-antibody reaction

agglutinin - a specific principle or antibody in blood serum; capable of causing the clumping of bacteria, blood corpuscles or particles; also called an isoantibody

agglutinogen - a genetically-determined antigen located on the surface of erythrocytes; basis for ABO grouping and Rh system of blood classification; also called an isoantigen

agnosia - loss of the ability to recognize the meaning of stimuli from the various senses (visual, auditory, tactile)

agraphia - an inability to write

airway disruption - Fractures or tears of the upper airway may occur without causing overt obstruction. However, they may impair ventilation and oxygenation. The diagnosis starts with an index of suspicion based on the mechanisms of injury and presenting problems such as stridor. A pneumothorax with subsequent large air leak following tube thoracostomy or the presence of mediastinal air are additional clues. Evaluation is usually carried out with the aid of flexible bronchoscopy. Definitive treatment will depend on the location and severity of the injury as well as the resources available. Temporizing measures include selective intubation and ventilation beyond the area of injury.

airway obstruction - Airway patency and air exchange can be assessed by examining for air movement and watching chest excursion, listening for stridor, and looking for obvious lower neck or upper chest injuries that may compromise the airway. If airway patency or the patient?s ability to protect the airway are in question, a more secure airway is needed. Endotracheal intubation is the first step, with care taken to protect against cervical injury. If an airway injury is suspected, rapid evaluation by means of flexible bronchoscopy may be necessary to identify the injury. Furthermore, bronchoscopy may be an aid in obtaining a patent airway, particularly in the patient who may have an unknown cervical spine injury. Emergency airway maneuvers such as cricothyroidotomy may also be necessary during this period.

albinism - abnormal, nonpathological, partial or total absence of pigment in skin, hair and eyes

albumin - the most abundant (60%) & smallest plasma protein; functions primarily to regulate osmotic pressure of plasma

albuminuria - presence of albumin in the urine

aldosterone - mineral corticoid produced by the adrenal cortex; brings about sodium and water reabsorption and potassium secretion

alimentary - pertaining to nutrition

alkaline - containing more hydroxyl ions (OH-) than hydrogen ions (H+) to produce a pH of more than 7

alkalosis - a condition in which blood pH ranges from 7.45 to 8.00 or higher

allantois - a small, vascularized membrane between the chorion and amnion of the fetus; serves as an early site for blood formation

alleles - genes that control the same inherited trait (such as height or eye color); they are located at the same position (locus) on homologous chromosomes

allergen - an antigen that evokes a hypersensitivity reaction

allergic - pertaining to or sensitive to an allergen

alveolus - a small hollow or cavity; an air sac in the lungs; milk-secreting portion of a mammary gland

Alzheimer's disease - disabling neurological disorder characterized by dysfunction and death of specific cerebral neurons; this results in widespread intellectual impairment, personality changes, and fluctuations in alertness

ambulatory - capable of walking

amenorrhea - absence of menstruation

amnesia - a lack or loss of memory

amniocentesis - removal of amniotic fluid by inserting a needle transabdominally into the amniotic cavity

amnion - innermost fetal membrane; a thin transparent sac that holds the fetus suspended in amniotic fluid; also called the bag of waters

amniotic fluid - fluid in the amniotic cavity, the space between the developing embryo (or fetus) and amnion; the fluid is produced initially as a filtrate from maternal blood and later, from fetal urine

amorphous - without definite shape or structural differentiation; pertains to solids without crystalline structure

amphiarthrosis - articulation in which the articulating bony surfaces are separated by an elastic substance to which both are attached; the mobility is slight, midway between a synarthrosis and a diarthrosis

ampulla - saclike dilation of a canal

amyotrophic - amyotrophic lateral sclerosis (ALS) - progressive neuromuscular disease characterized by spinal cord motor neuron degeneration that leads to muscular weakness; also called Lou Gehrig's disease

anabolism - synthetic energy-requiring reactions whereby small molecules are assembled into larger ones

anaerobic - not requiring molecular oxygen

analgesia - pain relief

anaphase - the third stage of mitosis in which the chromatids that have separated at the centromeres move to opposite poles of the cell

anaphylaxis - against protection; a hypersensitivity (allergic) reaction in which IgE antibodies attach to mast cells & basophils, causing them to produce mediators (e.g., histamine) leading to greater capillary permeability, smooth muscle contraction & mucus secretion

anastomosis - an end-to-end union or joining together of blood vessels, lymphatics or nerves

anatomical position - a position of the body universally used in anatomical descriptions in which the body is erect, facing the observer, the upper extremities are at the sides, the palms of the hands are facing forward, and the feet are on the floor

anatomy - the structure or study of structure of the body and the relation of its parts to each other

androgen - substance producing or stimulating male sex characteristics, e.g., the male hormone testosterone

anemia - condition of the blood in which the number of functional red blood cells or their hemoglobin content is below normal

anesthesia - total or partial loss of feeling or sensation, usually defined with respect to loss of pain sensation; may be general or local

aneuploid - a cell that has one or more chromosomes of a set added or deleted

aneurysm - a saclike enlargement of a blood vessel caused by a weakening of its wall

angina pectoris - pain in the chest related to reduced coronary circulation; it may or may not involve heart or artery disease

angiography - X-ray examination of blood vessels after injection of a radiopaque substance

angiotensin - either of two forms of a protein associated with regulation of blood pressure; angiotensin I, produced by action of renin on angiotensinogen, is converted by a plasma enzyme into angiotensin II which releases aldosterone

anion - a negatively charged ion; e.g., the chloride ion (Cl-)

ankyloglossia - tongue-tied; restriction of tongue movements by a short lingual frenulum

ankylosis - severe or complete loss of movement at a joint

anomaly - abnormality that may be a developmental (congenital) defect; a variant from the usual standard

anopsia - a defect in vision

anorexia nervosa - a chronic disorder characterized by severe self-induced weight loss, body-image and other perceptual disturbances, & physiological changes resulting from nutritional depletion

anosmia - loss of the sense of smell

antagonist - a muscle that has an action opposite that of the prime mover (agonist) and yields to the movement of the prime mover; a substance which blocks a receptor site where a specific molecule (agonist) binds

antepartum - before delivery of the child; occurring (to the mother) before childbirth

anterior - nearer to or at the front of the body; also called ventral

anti-oncogene - a gene that can cause cancer when inactivated inappropriately

antibiotic - literally, antilife; a chemical produced by a microorganism that is able to inhibit the growth of or kill other microorganisms

antibody - a protein produced by certain cells in the body in the presence of a specific antigen; the antibody combines with that antigen to neutralize, inhibit, or destroy it

anticoagulant - a substance that is able to delay, suppress, or prevent the clotting of blood

antidiuretic - substance that inhibits urine formation

antigen - any substance that when introduced into the tissues or blood induces the formation of antibodies and reacts only with its specific antibodies

antrum - any nearly closed cavity or chamber, especially one within a bone, such as a sinus

anulus fibrosus - a ring of fibrous tissue & fibrocartilage; encircles the pulpy substance (nucleus pulposus) of an intervertebral disc

anuria - a daily urine output of less than 50 ml

anus - the distal end and outlet of the rectum

aorta - the main systemic trunk of the arterial system of the body; emerges from the left ventricle

aortic injury - This is a dramatic injury because of the potential morbidity and mortality of the condition and its treatment. Typically this is seen when the mechanism of injury is rapid deceleration, resulting in differential forces on the proximal descending aorta between fixed and more mobile portions. Thus, the most common site of injury is just beyond the ligamentum arteriosum. In those patients who survive to be evaluated, the injury consists of a tear of the intima with containment of the blood by the adventitia and surrounding tissue. A periaortic hematoma results but usually there is no active bleeding. The hallmark sign is a widened mediastinum seen on chest radiograph, related to the adventitial hematoma. Diagnosis begins with a high index of suspicion based on the mechanism of injury, and a chest radiograph is obtained to identify alterations in the contour of the mediastinum and overall widening of the mediastinum. CT scans of the chest may help to delineate the changes seen on chest radiography, specifically hematoma around the affected portions of the aorta. The gold standard for the diagnosis, however, remains arterial angiography, usually directed at outlining the entire ascending, transverse arch, and proximal descending portions of the aorta.  All of these areas are at risk for blunt injury to the aorta.

Much has been written in recent years regarding alternative methods of diagnosis including more sophisticated chest CT scan techniques and the use of transesophageal echocardiography. In general, the CT scan has not provided the resolution needed for many surgeons to adequately localize the injury for subsequent treatment. Transesophageal echocardiography results are very dependent on the skill and experience of the operator. In addition, much of the transverse arch of the aorta is not well visualized with this modality. However, these tests can be valuable as screening methods or adjunctive imaging in cases where angiography is delayed or the findings are not definitive.

Treatment of blunt aortic injuries is usually performed by qualified trauma or thoracic surgeons. While the threat of rupture of the hematoma is always present, temporizing measures include hemodynamic monitoring and aggressive BP control, often aided by IV beta blockade. With such methods, definitive treatment can be delayed for hours or days if deemed necessary because of the patient?s condition or other injuries.

Recently, the use of endovascular techniques has been expanded to include selective use for tears of the proximal descending thoracic aorta.  Briefly, these techniques involve the percutaneous placement of intraluminal stents within the region of aortic aneurysms and dissections as an alternative to operative graft replacement. The morbidity of a transthoracic approach and the need for aortic cross clamping is eliminated. This treatment is still considered highly experimental but may become a viable option for trauma patients.

aperture - an opening or orifice

apex - the pointed end of a conical structure, such as the apex of the heart

apgar score - a method for assessing the overall status of an infant soon after birth; based on evaluation of heart rate, respiratory effort, muscle tone, reflex irritability, and color

aphasia - loss of ability to express oneself properly through speech, or loss of verbal communication

apnea - temporary cessation of breathing

apneustic area - portion of the respiratory center in the pons; sends stimulatory nerve impulses to the inspiratory area to activate and prolong inspiration and to inhibit expiration

apocrine gland - a type of gland in which the secretory products gather at the free end of the secreting cell and are pinched off, along with some of the cytoplasm, to become the secretion, as in the mammary glands

aponeurosis - a sheet like tendon joining one muscle with another or with bone

appendage - a structure attached to the body

appendicitis - inflammation of the vermiform appendix

appositional growth - growth due to surface deposition of material, as in the growth in diameter of cartilage and bone; also called exogenous growth

aqueduct - a canal or passage, especially for the conduction of a liquid

aqueous humor - the watery fluid, similar in composition to cerebro-spinal fluid, that fills the anterior cavity of the eye

arachnoid - the middle of the three coverings (meninges) of the brain or spinal cord

arbor vitae - the treelike appearance of the white matter tracts of the cerebellum when seen in midsagittal section; a series of branching ridges within the cervix of the uterus

areflexia - absence of reflexes

areola - any tiny space in a tissue; the pigmented ring around the nipple of the breast

arrector pili - smooth muscles attached to hairs; contraction pulls the hairs into a more vertical position, resulting in goose bumps

arrhythmia - irregular heart rhythm; also called dysrhythmia

arteriogram - roentgenogram of an artery after injection of a radi-opaque substance into the blood

arteriole - small, almost microscopic, artery that delivers blood to a capillary

artery - a blood vessel that carries blood away from the heart

arthritis - inflammation of a joint

arthrocentesis - insertion of a needle into a synovial (joint) cavity to remove a sample of synovial fluid, to relieve pressure, or to inject anesthetic or medication

arthrology - the study or description of joints

arthroscopy - a procedure for examining the interior of a joint, e.g., the knee, by inserting an arthroscope into a small incision; used to determine extent of damage, to remove torn cartilage, to repair cruciate ligaments, or to obtain samples for analysis

arthrosis - a joint or articulation

articular capsule - sleeve like structure around a synovial joint; composed of a fibrous capsule and a synovial membrane

articulate - to join together as a joint to permit motion between parts

articulation - a joint; a point of contact between bones, cartilage and bones, or teeth and bones

arytenoid - ladle-shaped

ascites - accumulation of serous fluid in the peritoneal cavity

aseptic - free from any infectious or septic material

asphyxia - unconsciousness due to interference with the oxygen supply of the blood

aspiration - inhalation of a foreign substance (water, food or foreign body) into the bronchial tree; drainage of a substance in or out by suction

astereognosis - inability to recognize objects or forms by touch

asthenia - lack or loss of strength; debility

astigmatism - irregularity of the lens or cornea of the eye causing an image to be out of focus and producing faulty vision

astrocyte - a neuroglial cell having a star shape; supports neurons in the brain and spinal cord and attaches neurons to blood vessels

ataxia - lack of muscular coordination; lack of precision

atelectasis - collapsed or airless state of all or part of the lung; may be acute or chronic

atherosclerosis - a process in which fatty substances are deposited in arterial walls in response to stimuli such as hypertension; following endothelial damage, white cells adhering to the walls take up cholesterol, etc., ultimately forming plaque that occludes the lumen

atresia - abnormal closure of a passage; abnormal absence of a normal body opening

atrial fibrillation - asynchronous contraction of the atria; results in the cessation of atrial pumping

atrial natriuretic factor - peptide hormone produced by the atria of the heart in response to stretching; it inhibits production of aldosterone and, thus, lowers blood pressure

atrioventricular bundle - portion of the heart's conduction system beginning at the AV node, passing through the cardiac skeleton between the atria and ventricles and into the interventricular septum where it splits into right and left bundle branches; also called bundle of His

atrium - a superior chamber of the heart
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- B -

Babinski sign - extension of the great toe, with or without fanning of the other toes, in response to stimulation of the outer margin of the sole of the foot; normal up to 1 1/2 years of age

Bainbridge reflex - the increased heart rate that follows increased pressure or distension of the right atrium

barium swallow - an X-ray examination of the upper gastrointestinal tract to evaluate for ulcers, tumors, & bleeding

baroreceptor - nerve cell capable of responding to changes in blood pressure; also called a pressoreceptor

basal metabolic rate - the rate of metabolism measured under standard or basal conditions

basilar membrane - a membrane in the cochlea of the inner ear that separates the cochlear duct from the scala tympani and on which the spiral organ (organ of Corti) rests

basophil - a type of white blood cell characterized by a pale nucleus and large granules that stain readily with basic dyes

benign - not malignant; favorable for recovery; mild disease

beta cell - a cell in the pancreatic islets (islets of Langer-hans); secretes insulin

bicuspid valve - atrioventricular (AV) valve on the left side of the heart; also called the mitral valve

bifurcate - having two branches or divisions; forked

bilateral - pertaining to two sides of the body

bile - a secretion of the liver consisting of water, bile salts, bile pigments, cholesterol, lecithin and several ions; it assumes a role in emulsification of fats prior to their digestion

biliary calculi - gallstones formed by cholesterol crystallization in bile

bilirubin - red pigment that is one of the end products of hemoglobin breakdown in liver cells; it is excreted as a waste material in the bile

bilirubinuria - presence of above-normal levels of bilirubin in urine

biliverdin - a green pigment that is one of the first products of hemoglobin breakdown in liver cells; it is converted to bilirubin or excreted as a waste material in bile

biopsy - removal of tissue or other material from the living body for examination, usually microscopic

blastocoel - the fluid-filled cavity within the blastocyst

blastocyst - in the development of an embryo, a hollow ball of cells that consists of a blastocoel (the internal cavity), trophoblast (outer cells), and inner cell mass

blastomere - one of the cells resulting from the cleavage of a fertilized ovum

blastula - an early stage in the development of a zygote

blepharism - spasm of the eyelids; continuous blinking

Bohr effect - in an acid environment, oxygen dissociates more readily from hemoglobin; hydrogen ions binding to hemoglobin alter its structure and reduce its oxygen-carrying capacity

bolus - soft, rounded mass, usually food, that is swallowed

bony labyrinth - a series of cavities within the petrous portion of the temporal bone forming the vestibule, cochlea, and semicircular canals of the inner ear

brachial plexus - a network of nerve fibers of the anterior rami of spinal nerves C5, C6, C7, C8 and T1; nerves emerging from the brachial plexus supply the upper extremity

Broca's area - motor area of the brain in the frontal lobe; translates thoughts into speech; also called the motor speech area

bronchi - branches of the respiratory passageway including primary bronchi (divisions of the trachea), secondary/ lobar bronchi (to the lobes of the lung) and tertiary/ segmental bronchi (to bronchopulmonary segments of the lung)

bronchial asthma - usually allergic reaction characterized by smooth muscle spasms in bronchi resulting in wheezing and difficult breathing

bronchiectasis - a chronic disorder in which there is a loss of normal tissue & expansion of lung air passages; characterized by difficult breathing, coughing, expectoration of pus, and foul breath

bronchiole - branch of tertiary bronchus further subdividing into terminal bronchioles (to lobules of lung), which divide into respiratory bronchioles (to alveolar sacs)

bronchitis - inflammation of bronchi characterized by hypertrophy and hyperplasia of seromucous glands and goblet cells that line the bronchi, resulting in a productive cough

bronchogenic carcinoma - cancer originating in the bronchi

bronchogram - a roentgenogram of the bronchial tree

bronchography - technique for examining the bronchial tree in which an opaque contrast medium is introduced into the trachea for distibution to the bronchial branches; produces a bronchogram

bronchopulmonary segment - one of the smaller divisions of a lobe of a lung supplied by its own branches of a bronchus

bronchoscope - an instrument used to examine the interior of the bronchi of the lungs

bronchoscopy - visual examination of the interior of the trachea and bronchi with a bronchoscope to biopsy a tumor, to clear an obstruction, to take cultures, to stop bleeding, or to deliver drugs

bronchus - one of the two large branches of the trachea

buccal - pertaining to the cheek or mouth

bulbourethral gland - one of a pair of glands located inferior to the prostate gland on either side of the urethra; it secretes an alkaline fluid into the cavernous urethra; also called a Cowper's gland

bulimia - a disorder characterized by overeating, at least twice a week, followed by purging by self-induced vomiting, strict dieting or fasting, vigorous exercise, or use of laxatives

bullae - blisters beneath or within the epidermis

bunion - lateral deviation of the great toe; produces inflammation and thickening of the bursa, bone spurs, and calluses

bursa - a sac or pouch of synovial fluid located at friction points, especially about joints

bursitis - inflammation of a bursa

buttocks - the two fleshy masses on the posterior aspect of the lower trunk, formed by the gluteal muscles
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- C -

cachexia - a state of ill health

calcification - deposition of mineral salts, primarily hydroxyapatite, in a framework formed by collagen fibers in which the tissue hardens

calcitonin - hormone produced by the parafollicular cells of the thyroid gland; it lowers calcium and phosphate levels of the blood by inhibiting bone breakdown and accelerating calcium absorption by bones

calculus - a stone, or insoluble mass of crystallized salts or other material, formed within the body, as in the gallbladder, the kidney, or the urinary bladder

callus - a growth of new bone tissue in & around a fractured area, ultimately replaced by mature bone; acquired, localized thickening

calmodulin - intracellular protein that binds with calcium ions and activates or inhibits enzymes, many of which are protein kinases, to elicit physiological responses of hormones

calorie - the standard LETTER of heat; the amount of heat necessary to raise 1 g of water from 14 to 15 degrees C; the kilocalorie, used in metabolic and nutritional studies, is the amount of heat necessary to raise 1,000 g of water 1 degree C and is equal to 1,000 cal

calyx - any of the cuplike divisions of the kidney pelvis; plural, calyces

canaliculus - a small channel or canal, as in bones, where they connect lacunae; plural, canaliculi

cancellous - having a reticular or latticework structure, as in spongy tissue of bone

canker sore - painful ulcer on the mucous membrane of the mouth; it may result from an autoimmune response

capacitation - the functional changes that sperm undergo in the female reproductive tract; these changes allow them to fertilize a secondary oocyte

capillary - a microscopic blood vessel located between an arteriole and venule through which materials can be exchanged between blood and body cells

carbohydrate - organic compound containing carbon, hydrogen, and oxygen in a particular amount and arrangement.

carcinoembryonic antigen - a glycoprotein secreted by normally developing fetal tissue during the first or second trimester, after birth, and in certain malignant and benign conditions

carcinogen - any substance that causes cancer

carcinoma - a malignant tumor consisting of epithelial cells

cardiac arrest - cessation of an effective heartbeat; the heart may stop completely or undergo ventricular fibrillation

cardiac catheterization - introduction of a catheter into the heart and/or its blood vessels to: measure pressure; assess left ventricular function & cardiac output; measure blood flow & oxygen content; assess valve & conduction system status; identify septal or valvular defects

cardiac tamponade - While this injury is more common in penetrating trauma, blunt chest trauma also may result in rupture of a cardiac structure. It may be of a degree that does not result in rapid and fatal exsanguination immediately, but rather causes so much blood to accumulate within the pericardium that it begins to exert pressure on the heart. The most susceptible areas are the vena cava and atria, resulting in depressed venous return to the heart and subsequent hemodynamic instability. Classically the diagnosis can be made by Beck?s triad: increased jugular venous distention (or elevated central venous pressure, if monitored), muffled heart sounds, and hypotension. The heart sounds may be difficult to hear in the emergency department. A globular appearance of the pericardium on a chest radiograph also may be suggestive of this injury. Initial treatment usually consists of some type of rapid evacuation of the pericardial space, either via a pericardiocentesis or subxiphoid pericardial window. Emergent thoracotomy, also known as a resuscitative thoracotomy or emergency room thoracotomy, is classically performed through the left anterolateral approach in the intercostal region in the lower half of the chest. This allows access to the pericardium to relieve tamponade. It may also allow open massage of the heart and clamping of the descending thoracic aorta to try to maintain blood flow to the cerebral region. Although its benefit has been described in penetrating chest injuries, multiple other reports have shown its futility in blunt chest cases. Experiences to date have found that victims who arrive pulseless and unresponsive to all other measures have uniformly not responded to emergency thoracotomy.

cardioacceleratory center - a group of neurons in the medulla from which cardiac sympathetic nerves arise; nerve impulses along these nerves release norepinephrine that increases the rate and force of the heartbeat

cardioinhibitory center - a group of neurons in the medulla from which arise parasympathetic fibers that reach the heart via the vagus (X) nerve; nerve impulses along these nerves release acetylcholine that decreases the rate & force of the heartbeat

cardiology - the study of the heart and its associated diseases

cardiopulmonary resuscitation - CPR; technique employed to restore life or consciousness to a person apparently dead or dying; includes external respiration (exhaled air respiration) & external cardiac massage

cardiovascular center - groups of neurons scattered within the medula that regulate heart rate, force of contraction, and blood vessel diameter

carina - a ridge on the inside of the division of the right and left primary bronchi

carotid body - receptor on or near the carotid sinus that responds to alterations in blood levels of oxygen, carbon dioxide, and hydrogen ions

carpus - a collective term for the eight bones of the wrist

cartilage - a type of connective tissue consisting of chondrocytes in lacunae embedded in dense network of collagenous and elastic fibers in a matrix of chondroitin sulfate

cartilaginous joint - a joint without a synovial (joint) cavity where the articulating bones are held tightly together by cartilage, allowing little or no movement

caruncle - a small, fleshy eminence, often abnormal

castration - the removal of the testes

catabolism - chemical reactions involving the break down of complex organic compounds into simple ones with the release of energy

cataract - loss of transparency of the lens of the eye or its capsule or both

catheter - a tube that can be inserted into a body cavity through a canal or into a blood vessel; used to remove fluids, such as urine and blood, and to introduce diagnostic materials or medication

cation - a positively charged ion; an example is a sodium ion

cauda equina - a tail like collection of roots of spinal nerves at the inferior end of the spinal canal

caudal - pertaining to any tail like structure; inferior in position

cecum - blind pouch at the proximal end of the large intestine below the terminal portion of the ileum

celiac - pertaining to the abdomen

cementum - calcified tissue covering the root of a tooth

centrioles - paired, cylindrical structures within a centrosome, each consisting of a ring of microtubules; arranged at right angles to each other; function in cell division to organize the spindle apparatus

centromere - the clear constricted portion of a chromosome where the two chromatids are joined; serves as the point of attachment for the chromosomal microtubules

centrosome - dense area of cytoplasm, near the nucleus of a cell, containing a pair of centrioles

cephalic - pertaining to the head; superior in position

cerebellar peduncle - a bundle of nerve fibers connecting the cerebellum with the brain stem

cerebellum - the portion of the brain lying posterior to the medulla and pons, concerned with coordination of movements

cerebral aqueduct - a channel through the mid-brain connecting the third and fourth ventricles and containing cerebrospinal fluid

cerebral palsy - a group of motor disorders resulting in muscular uncoordination and loss of muscle control caused by damage to motor areas of the brain (cerebral cortex, basal ganglia, cerebellum) during fetal life, birth, or infancy

cerebrospinal fluid - a fluid produced in the choroid plexuses and ependymal cells of the ventricles of the brain; it circulates in the ventricles and the subarachnoid space around the brain and spinal cord

cerebrovascular accident - destruction of brain tissue (infarction) resulting from disorders of blood vessels that supply the brain (also called a stroke)

cerebrum - the two hemispheres of the forebrain, making up the largest part of the brain

ceruminous gland - a modified sudoriferous (sweat) gland in the external auditory meatus; it secretes cerumen (ear wax)

cervical dysplasia - change in the growth, number, and shape of cervical cells of the uterus that, if severe, may progress to cancer

cervix - neck; any constricted portion of an organ, such as the lower cylindrical part of the uterus

cesarean section - procedure in which a low, horizontal incision is made through the abdominal wall and uterus for removal of the baby and placenta; also called a C-section

chalazion - a small tumor of the eyelid

chemiosmosis - process by which energy released is used to generate ATP when a substance moves along a gradient

chemonucleolysis - dissolution of the nucleus pulposus of an intervertebral disc by injection of a proteolytic enzyme (chymopapain) to relieve pressure and pain associated with a herniated (slipped) disc

chemoreceptor - receptor that detects the presence of chemicals; e.g., outside the central nervous system on or near the carotid and aortic bodies

chemotaxis - attraction by a chemical stimulus, e.g., phagocytes to microbes

chemotherapy - the treatment of illness or disease by chemicals

chiasma - a crossing; especially the crossing of the optic (II) nerve fibers

chiropractic - a system of treating disease by using one's hands to manipulate body parts, mostly the vertebral column

chlamydia - organism causing a sexually transmitted disease characterized by burning on urination, frequent and painful urination, and low back pain; may spread to uterine (Fallopian) tubes in females

choana - a funnel-shaped structure; the posterior opening of the nasal fossa, or internal nares

cholecystectomy - surgical removal of the gallbladder

cholesterol - classified as a lipid, the most abundant steroid in animal tissues; located in cell membranes and used for synthesis of steroid hormones and bile salts

cholinergic fiber - nerve ending that liberates acetylcholine at a synapse

cholinesterase - an enzyme that hydrolyzes acetylcholine

chondrocyte - cell of mature cartilage

chondroitin sulfate - amorphous matrix material found outside of cells

chordae tendineae - tendon like, fibrous cords that connect the heart valves with the papillary muscles

chorion - the outermost fetal membrane; becomes the principle embryonic portion of the placenta; serves a protective and nutritive function

chorionic villus - fingerlike projection of the chorion; it grows into the decidua basalis of the endometrium and contains fetal blood vessels

choroid - one of the vascular coats of the eyeball

chromaffin cell - cell that has an affinity for chrome salts, owing in part to the presence of the precursors of the neuro-transmitter epinephrine; found, among other places in the adrenal medulla

chromatid - one of a pair of identical connected nucleoprotein strands that are joined at the centromere and separate during cell division, each becoming a chromosome of one of the two daughter cells

chromatin - threadlike mass of genetic material consisting principally of DNA; it is present in the nucleus of a non-dividing or interphase cell

chromatolysis - the breakdown of chromatophilic substance (Nissl bodies) into finely granular masses in the cell body of a central or peripheral neuron whose process (axon or dendrite) has been damaged

chromosome - one of the 46 small, dark-staining bodies that appear in the nucleus of a human diploid (2n) cell during cell division

chronic - long-term or frequently recurring; applied to a disease that is not acute

chyle - the milky fluid found in the lacteals of the small intestine after digestion

chyme - the semi-fluid mixture of partly digested food and digestive secretions found in the stomach and small intestine during digestion of a meal

cicatrix - a scar left by a healed wound

ciliary body - one of the three portions of the vascular tunic of the eyeball, the others being the choroid and the iris; includes the ciliary muscle and the ciliary processes

cilium - a hair or hair like process projecting from a cell that may be used to move the entire cell or to move substances along the surface of the cell

circadian rhythm - a cycle of active and non-active periods in organisms determined by internal mechanisms, repeating about every 24 hours

circumcision - surgical removal of the foreskin (prepuce), the fold of skin over the glans penis

circumduction - a movement at a synovial joint in which the distal end of a bone moves in a circle while the proximal end remains relatively stable

circumvallate papilla - one of the circular projections that is arranged in an inverted V-shaped row at the posterior portion of the tongue; the largest of the elevations on the upper surface of the tongue containing taste buds

cirrhosis - a liver disorder in which the parenchymal cells are destroyed and replaced by connective tissue

cisterna chyli - the origin of the thoracic duct

climacteric - cessation of the reproductive function in the female or diminution of testicular activity in the male

clitoris - female erectile organ located at the anterior junction of the labia minora; it is homologous to the male penis

clone - a population of cells identical to itself

coagulation - process by which a blood clot is formed

coarctation of the aorta - a congenital condition in which the aorta is too narrow; it results in reduced blood supply, increased ventricular pumping, and high blood pressure

coccyx - the fused bones at the end of the vertebral column

cochlea - a winding, cone-shaped tube forming a portion of the inner ear and containing the spiral organ (organ of Corti)

coitus - sexual intercourse; also called copulation

colitis - inflammation of the mucosa of the colon and rectum; absorption of water and salts is reduced, producing watery, bloody feces, and, in severe cases, dehydration and salt depletion; spasms of the muscularis produce cramps

collagen - a protein that is the main organic constituent of connective tissue

colliculus - a small elevation

colostomy - creating a surgical opening through the exterior abdominal wall into the colon for the diversion of feces

colostrum - thin, cloudy fluid secreted by the mammary glands a few days prior to or after delivery before true milk is secreted

colposcopy - direct examination of the vaginal & cervical mucosa using a magnifying device; frequently the first procedure performed following an abnormal Pap smear

coma - final stage of brain failure; it is characterized by total unresponsiveness to all external stimuli

commissure - the angular junction of the eyelids at either corner of the eyes

complement - a group of at least twenty proteins found in serum and forming a component of nonspecific resistance and immunity by bringing about cytolysis, inflammation, and opsonization

computed tomography (CT) - X-ray technique that provides a cross-sectional image of any area of the body; also called computed axial tomography (CAT)

concha - a scroll-like bone found in the skull; plural, conchae

concussion - a traumatic injury to the brain that produces no visible bruising but may cause abrupt, temporary loss of conciousness

conductivity - ability to carry the effect of a stimulus from one part of a cell to another; highly developed in nerve and muscle fibers (cells)

congenital - present at the time of birth

conjunctiva - delicate membrane covering the eyeball and lining the eyelids

conjunctivitis - inflammation of the conjunctiva, the delicate membrane covering the eyeball & lining the eyelids

constipation - infrequent or difficult defecation resulting from decreased intestinal motility

contraception - the prevention of conception or impregnation with-out destroying fertility

contractility - ability of cells or parts of cells actively to generate force leading to shortening and change of form for purposeful movements; muscle fibers (cells) display a high degree of contractility

contralateral - on the opposite side; affecting the opposite side of the body

contusion - condition in which tissue below the skin is damaged, but the skin is not broken

conus medullaris - the tapered portion of the spinal cord below the lumbar enlargement

convergence - arrangement in which synaptic end bulbs of more than one presynaptic neuron terminate on one postsynaptic neuron; medial movement of the two eye-balls so that both are directed at a close object being viewed so that a single image is produced

convulsion - violent, involuntary, tetanic contractions of an entire group of muscles

cor pulmonale (CP) - right ventricular hypertrophy from disorders that bring about hypertension in pulmonary circulation

cornea - the nonvascular, transparent fibrous coat of the eye through which the iris can be seen

corona - margin of the glans penis

coronary angiography - a procedure in which the severity and location of blocked coronary arteries are visualized by injection of contrast dyes or in which clot-dissolving drugs may be injected into coronary arteries

coronary sinus - a wide venous channel on the posterior surface of the heart that collects the blood from the coronary circulation and returns it to the right atrium

corpora quadrigemina - the four small elevations (superior and inferior colliculi) on the dorsal region of the midbrain concerned with visual and auditory functions

corpus albicans - a white fibrous patch in the ovary that forms after regression of the corpus luteum

corpus callosum - the great commissure of the brain connecting the cerebral hemispheres

corpus luteum - a yellow endocrine gland in the ovary formed when a follicle has discharged its secondary oocyte; secretes estrogens, progesterone, and relaxin

corpus striatum - an area in the interior of each cerebral hemisphere composed of the caudate and lentiform nuclei of the basal ganglia and the white matter of the internal capsule, arranged in a striated manner

cortex - an outer layer of an organ; the convoluted layer of gray matter covering each cerebral hemisphere

costal cartilage - the hyaline cartilage that attaches each rib to the sternum

cranial cavity - a subdivision of the dorsal body cavity; formed by the cranial bones and containing the brain

craniosacral outflow - fibers of parasympathetic preganglionic neurons; they have their cell bodies located in nuclei in the brain stem and in the lateral gray matter of the sacral portion of the spinal cord

craniotomy - any operation on the skull, as for surgery on the brain or for decompression of the fetal head in difficult labor

cranium - the portion of the skull that protects the brain and the organs of sight, hearing, and balance; includes the frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones

creatine phosphate - high-energy molecule in skeletal muscle cells that is used to generate ATP rapidly; on decomposition, creatine phosphate breaks down into creatine, phosphate, and energy?the energy is used to generate ATP from ADP

crenation - the shrinkage of red blood cells into knobbed, starry forms when placed in a hypertonic solution

cretinism - severe congenital thyroid deficiency during childhood leading to physical and mental retardation

crista - a crest or ridged structure; a small elevation in the ampulla of each semicircular duct that serves as a receptor for dynamic equilibrium

crus of penis - separated, tapered portion of the corpora cavernosa penis; plural, crura

cryosurgery - the destruction of tissue by application of extreme cold

cryptorchidism - the condition of having undescended testes

cupula - the mass of gelatinous material covering the hair cells of a crista, a receptor in the ampulla of a semicircular canal that is stimulated when the head moves

curvature - a nonangular deviation of a straight line, as in greater and lesser curvatures of the stomach; abnormal curvatures of the vertebral column include kyphosis, lordosis, and scoliosis

cutaneous - pertaining to the skin

cyanosis - reduced (unoxygenated) hemoglobin concentration in blood of more than 5 g/dl; it results in a blue or dark purple discoloration that is most easily seen in the nail beds and mucous membranes

cyst - a sac with a distinct connective tissue wall, containing a fluid or other material

cystic duct - the duct that transports bile from the gallbladder to the common bile duct

cystitis - an inflammation of the urinary bladder

cystoscope - instrument used to examine the inside of the urinary bladder

cystoscopy - direct visual examination of the urinary tract (and prostate gland in males as well) using a cystoscope to evaluate urinary tract disorders & to remove tissue for biopsy, kidney stones, urinary bladder tumors, & urine samples

cytochrome - one of a series of proteins with an iron-containing (heme) group, capable of alternating between a reduced and an oxidized form

cytokine - growth factor produced by activated lymphocytes and other cells that acts as an autocrine or paracrine and has various roles in immunity and blood cell development

cytokinesis - division of the cytoplasm

cytology - the study of cells

cytoplasm - substance that surrounds organelles and is located within a cell's plasma membrane, external to its nucleus; also called protoplasm

cytosol - semi-fluid portion of cytoplasm in which organelles and inclusions are suspended and solutes are dissolved?also called intracellular fluid
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- D -

dartos - contractile tissue under the skin of the scrotum

debility - weakness of tonicity in functions or organs of the body

decibel (db) - a LETTER of measurement for relative sound intensity (loudness)

decidua - that portion of the endometrium of the uterus (all but the deepest layer) that is modified for pregnancy and shed after childbirth

deciduous - falling off or being shed seasonally or at a particular stage of development; in the body, referring to the first set of teeth

decubitus ulcer - tissue destruction due to a constant deficiency of blood to tissues overlying a bony projection subjected to prolonged pressure against an object like a bed, cast, or splint; also bedsore, pressure sore, trophic ulcer

decussation - a crossing-over; usually refers to the crossing of most of the fibers in the large motor tracts to opposite sides in the medullary pyramids

deep fascia - a sheet of connective tissue wrapped around a muscle to hold it in place

defecation - discharge of feces from the rectum

defibrillation - delivery of a very strong electrical current to the heart in an attempt to stop ventricular fibrillation

degeneration - a change from a higher to a lower state; a breakdown in structure

deglutition - the act of swallowing

dehydration - excessive water loss from the body or its parts

delirium - a transient disorder of abnormal cognition (perception, thinking or memory) and disordered attention, accompanied by disturbance of sleep-wake cycles and psychomotor behavior; also called acute confusional state (ACS)

dementia - an organic mental disorder resulting in permanent or progressive general loss of intellectual abilities (e.g., memory, judgement, and abstract thinking) and changes in personality; most common cause is Alzheimer's disease

demineralization - loss of calcium and phosphorus from bones

denaturation - disruption of the tertiary structures of a protein by agents, such as heat, pH changes, or other physical or chemical methods; as a result, the protein loses its physical and biological properties

dendrite - a nerve cell process that carries a nerve impulse toward the cell body

dendritic cell - one type of antigen-presenting cell with long branchlike projections, for example, Langerhans cells in the epidermis

dens - tooth

dental caries - gradual demineralization of the enamel and dentin of a tooth; it may invade the pulp and alveolar bone; also called tooth decay

denticulate - finely toothed or serrated; characterized by a series of small, pointed projections

dentin - osseus tissues of a tooth, enclosing the pulp cavity

dentition - the eruption of teeth; the number, shape and arrangement of teeth

deoxyribonucleic acid/DNA - nucleic acid in the shape of a double helix; constructed of nucleotides consisting of 1 of 4 nitrogenous bases (adenine, cytosine, guanine, or thymine), deoxyribose, and a phosphate group; the genetic information is encoded in the nucleotides

depolarization - in neurophysiology, the reduction of voltage across a cell membrane; expressed as a movement toward less negative (more positive) voltages on the interior side of the cell membrane

depression - movement in which a part of the body moves downward

dermatology - medical specialty dealing with diseases of the skin

dermatome - an instrument for incising the skin or cutting thin transplants of skin; the cutaneous area developed from one embryonic spinal cord segment and receiving most of its innervation from one spinal nerve

dermis - a layer of dense connective tissue lying deep to the epidermis; the true skin or corium

detritus - particulate matter produced by or remaining after the wearing away or disintegration of a substance or tissue; scales, crusts, or loosened skin

detrusor muscle - muscle in the wall of the urinary bladder

diabetes insipidus - condition caused by hyposecretion of antidiuretic hormone (ADH) and characterized by thirst and by excretion of large amounts of urine

diabetes mellitus - hereditary condition caused by hyposecretion of insulin; characterized by hyperglycemia, increased urine production, excessive thirst and excessive eating

diagnosis - distinguishing one disease from another or determining the nature of a disease from signs and symptoms by inspection, palpation, laboratory tests, and other means

dialysis - the process of separating small molecules from large by the difference in their rates of diffusion through a selectively permeable membrane

diapedesis - the passage of white blood cells through intact blood vessel walls

diaphragm - partition separating one area from another, e.g., the dome-shaped skeletal muscle between the thoracic and abdominal cavities; or a dome-shaped structure that fits over the uterine cervix, usually with a spermicide, to prevent conception

diaphragmatic injury - Diaphragmatic injury typically results from the rapid increase in intra-abdominal pressure related to an episode of blunt trauma with subsequent rupture of the diaphragm. This is suspected based on the mechanisms of injury and radiographic appearance.3,28 As opposed to the defects seen with penetrating trauma, the defects in blunt trauma usually are larger and more often result in immediate herniation of abdominal contents. When the defect is small, herniation may occur over a period of weeks to months. This gradual occurrence is related in part to the differential between intrathoracic and intra-abdominal pressures.

The diagnosis may be difficult in part because the force of injury is likely to result in multiple organ damage, which will command the resuscitation team?s attention. The chest radiograph will often be abnormal, showing opacification within the affected pleural cavity, air fluid levels, and mediastinal shift. Compression of the lung may also occur. The findings may be mistaken for primary lung collapse, pleural fluid, or hematoma.

While rupture of the right diaphragm occurs in about one third of cases, the liver appears to protect against significant organ herniation into the right pleural space. Therefore, most cases seem to involve the left side, and the stomach is the most common organ involved. Thus, nasogastric tube placement can be helpful in making the diagnosis by chest radiography alone. Barium studies of the GI tract are another important diagnostic modality. It is important to keep diaphragmatic rupture in mind when performing tube thoracostomy for a suspected hematoma. Digital exploration of the pleural cavity prior to tube placement may be valuable. Treatment for acute cases usually involves laparotomy for reduction of the herniated contents, inspection for other intra-abdominal injury, and diaphragm repair.

diaphysis - the shaft of a long bone

diarrhea - frequent defecation of liquid feces caused by increased intestinal motility

diarthrosis - articulation in which opposing bones move freely, as in a hinge joint

diastole - in the cardiac cycle, the phase of relaxation or dilation of the heart muscle, especially, the ventricles

diastolic blood pressure - the force exerted by blood on arterial walls during ventricular relaxation; the lowest blood pressure measured in the large arteries, about 80 mm Hg under normal conditions for a young, adult male

diencephalon - part of the brain consisting primarily of the thalamus and the hypothalamus

differential - a white blood cell count that reports the number of each kind of white blood cell in a sample of 100 cells

differentiation - the acquisition of specific functions different from those of the original general type

diffusion - a passive process in which there is a net or greater movement of molecules or ions from a region of high concentration to a region of low concentration until equilibrium is reached

digestion - mechanical and chemical breakdown of food to simple molecules that can be absorbed and used by body cells

dilate - to expand or swell

dilation and curettage - following dilation of the uterine cervix, the uterine endometrium is scraped with a curette (spoon-shaped instrument); also called a D and C

diploid - having the number of chromosomes characteristically found in somatic cells of an organism; symbolized 2n

diplopia - double vision

dislocation - the displacement of a bone from a joint with tearing of ligaments, tendons, and articular capsules; also called luxation

dissect - to separate tissues & parts of a cadaver (corpse) or an organ for anatomical study

dissociation - the separation of inorganic acids, bases, and salts into ions when dissolved in water; also called ionization

distal - farther from the attachment of an extremity to the trunk or to a structure; farther from the point of origin

diuretic - chemical that inhibits sodium reabsorption, reduces antidiuretic hormone (ADH) concentration, & increases urine volume by inhibiting facultative reabsorption of water

diurnal - repeating daily; pertaining to daylight hours (opposite: nocturnal)

divergence - an anatomical arrangement in which the synaptic end bulbs of one presynaptic neuron terminate on several postsynaptic neurons

diverticulitis - inflammation of diverticula, saclike outpouchings of the colonic wall, when the muscularis becomes weak

diverticulum - sac or pouch in the wall of a canal or organ, especially in the colon

donor insemination - deposition of seminal fluid within the vagina or cervix at a time during the menstrual cycle when pregnancy is likely; may be homologous (husband's semen) or heterologous (donor's semen); also called artificial insemination

dorsal ramus - a branch of a spinal nerve containing motor and sensory fibers supplying the muscles, skin, and bones of the posterior part of the head, neck, and trunk

dorsiflexion - bending the foot in the direction of the dorsum (upper surface)

dropsy - a condition in which there is abnormal accumulation of water in the tissues and cavities

ductus arteriosus - a small vessel connecting the pulmonary trunk with the aorta; found only in the fetus

ductus epididymis - tightly coiled tube inside the epididymis, distinguished into a head, body, and tail; it is the site where spermatozoa under-go maturation

ductus (vas) deferens - duct that conveys spermatozoa from the epididymis to the ejaculatory duct; also called the seminal duct

ductus venosus - a small vessel in the fetus that helps the circulation bypass the liver

duodenal gland - gland in the submucosa of the duodenum that secretes an alkaline mucus to protect the lining of the small intestine from the action of enzymes & to help neutralize the acid in chyme; also called Brunner's gland

duodenum - the first 25 cm (10 in.) of the small intestine

dura mater - outer membrane (meninx) covering the brain and spinal cord

dynamic equilibrium - the maintenance of body position, mainly the head, in response to sudden movements such as rotation

dysfunction - absence of complete normal function

dyslexia - impairment of the brain's ability to translate images received from the eyes or ears into understandable language

dysmenorrhea - painful menstruation

dysphagia - difficulty in swallowing

dysplasia - change in the size, shape, and organization of cells due to chronic irritation or inflammation; may revert to normal if stress is removed or may progress to neoplasia

dyspnea - shortness of breath

dystocia - difficult labor due to such factors as pelvic deformities, malpositioned fetus, and premature rupture of fetal membranes

dystrophia - progressive weakening of a muscle

dysuria - painful urination
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- E -

echocardiogram - a procedure in which high frequency sound waves directed at the heart are reflected back and the echoes are picked up by a transducer and converted to an image

ectopic - out of the normal location

eczema - a skin rash characterized by itching, swelling, blistering, oozing, and scaling of the skin

edema - an abnormal accumulation of interstitial fluid

effector - an organ of the body, either a muscle or a gland, that responds to a motor neuron impulse

efferent arteriole - vessel of the renal vascular system that transports blood from the glomerulus to the peritubular capillary

effusion - escape of fluid from the lymphatics or blood vessels into a cavity or into tissues

ejaculation - reflex ejection of semen from the penis

ejaculatory duct - the tube that transports spermatozoa from the ductus (vas) deferens to the prostatic urethra

elasticity - ability of tissue to return to its original shape after contraction or extension

electrocardiogram - a recording of the electrical changes accompanying the cardiac cycle that can be recorded on the body's surface; may be resting, stress, or ambulatory

electroencephalogram /EEG - a recording of electrical impulses of the brain to diagnose certain diseases (such as epilepsy), to furnish information regarding sleep and wakefulness, and to confirm brain death

electrolyte - any compound that separates into ions when dissolved in water and that is able to conduct electricity

electromyography - evaluation of the electrical activity of resting or contracting muscle to find the causes of muscular weakness, paralysis, involuntary twitching, & abnormal levels of muscle enzymes; also used as part of biofeedback studies

eleidin - a translucent substance found in the stratum lucidum of the epidermis

elevation - movement in which a part of the body moves upward

ellipsoidal joint - a synovial joint in which an oval-shaped condyle of one bone fits into an elliptical cavity of another bone, permitting side-to-side and back-and-forth movements; e.g., the wrist joint between the radius and carpals; also called a condyloid joint

embolism - obstruction or closure of a vessel by an embolus

embolus - a blood clot, an air bubble, fat from broken bones, a mass of bacteria, or other debris or foreign material transported by the blood

embryo - the young of any organism in an early stage of development; in humans, the developing organism from fertilization to the end of the eighth week in utero

embryology - the study of development from the fertilized egg to the end of the eighth week in utero

emesis - vomiting

emmetropia - the ideal optical condition of the eyes

emphysema - a swelling or inflation of air passages due to loss of elasticity in the alveoli

emulsification - the dispersion of large fat globules into smaller uniformly distributed particles in the presence of bile

enamel - the hard, white substance covering the crown of a tooth

endocardium - the layer of the heart wall composed of endothelium and smooth muscle; it lines the inside of the heart and covers the valves and tendons that hold the valves open

endochondral ossification - replacement of cartilage by bone; also called intracartilaginous ossification

endocrine gland - any ductless gland that secretes hormones into the blood

endocrinology - the science concerned with the structure and functions of endocrine glands and the diagnosis and treatment of disorders of the endocrine system

endocytosis - uptake into a cell of large molecules and particles in which a segment of plasma membrane surrounds the substance, encloses it, and brings it in; includes phagocytosis, pinocytosis, and receptor-mediated endocytosis

endodontics - a branch of dentistry concerned with the prevention, diagnosis, and treatment of diseases that affect the pulp, root, periodontal ligament, and alveolar bone

endogenous - growing from or beginning within the organism

endolymph - the fluid within the membranous labyrinth of the inner ear

endometriosis - the growth of endometrial tissue outside the uterus

endometrium - the mucous membrane lining the uterus

endomysium - an invagination of the perimysium separating each individual muscle fiber (cell)

endoneurium - connective tissue wrapping around individual nerve fibers (cells)

endoplasmic reticulum (ER) - network of channels that run through the cytoplasm of a cell serving in intracellular transport, support, storage, synthesis, and packaging of molecules; some portions may have ribosomes attached (rough ER) & some lack ribosomes (smooth ER)

endorphin - a neuropeptide in the central nervous system that acts to reduce pain

endoscope - an illuminated tube with lenses used to look inside hollow organs such as the stomach (gastroscope) or the urinary bladder (cystoscope)

endoscopy - visual examination of any cavity of the body using an endoscope, an illuminated tube with lenses

endosteum - a membrane that lines the medullary cavity of bones, consisting of osteoprogenitor cells and scattered osteoblasts

endothelium - a layer of simple squamous epithelium that lines the cavities of the heart & the blood & lymphatic vessels

enkephalin - a peptide found in the central nervous system that acts to relieve pain

enteroendocrine cell - stomach cell that secretes the hormone gastrin

enterogastric reflex - reflex that inhibits gastric secretion; initiated by food in the small intestine

enuresis - involuntary discharge of urine, complete or partial, after age 3

enzyme - substance that affects the speed of chemical changes; an organic catalyst, most often a protein

eosinophil - a type of white blood cell characterized by granular cytoplasm readily stained by eosin

ependymal cells - neuroglial cells that line ventricles of the brain and probably assist in circulation of cerebrospinal fluid (CSF); also called ependymocytes

epicardium - the thin outer layer of the heart wall, composed of serous tissue & mesothelium; also called the visceral pericardium

epidemic - a disease that occurs above the expected level among individuals in a population

epidemiology - medical science concerned with the occurrence and distribution of disease in human populations

epidermis - outermost, thinner layer of skin, composed of stratified squamous epithelium

epididymis - comma-shaped organ lying along the posterior border of the testis & containing the ductus epipidymis in which the sperm mature; plural, epididymides

epidural space - a space between the spinal dura mater and the vertebral canal containing loose connective tissue and a plexus of veins

epiglottis - a large, leaf-shaped peice of cartilage lying on top of the larynx; its stem is attached to the thyroid cartilage and its leaf portion is unattached and free to move up and down to cover the glottis (vocal folds and rima glottidis)

epilepsy - neurological disorder that is characterized by short periodic attacks of motor, sensory, or psychological malfunction

epimysium - fibrous connective tissue around muscles

epinephrine - hormone secreted by the adrenal medulla; it produces actions similar to those that result from sympathetic stimulation; also called adrenaline

epineurium - the outermost covering around the entire nerve

epiphyseal plate - a cartilaginous plate between the epiphysis & the diaphysis; it is responsible for the lengthwise growth of long bones

epiphysis - the end of a long bone; it is usually larger in diameter than the shaft (diaphysis)

episiotomy - a cut made with surgical scissors to avoid tears in the perineum at the end of the second stage of labor

epistaxis - loss of blood from the nose due to trauma, infection, allergy, neoplasm, & bleeding disorders; also called nosebleed

epithelial tissue - tissue that forms glands or the outer part of the skin; it lines blood vessels, hollow organs, and passages that lead from the body to the exterior

eponychium - a narrow band of stratum corneum at the proximal border of a nail, extending from the nail margin; also called the cuticle

erection - the enlarged and stiffened state of the clitoris or the penis, resulting from the engorgement of the spongy erectile tissue with blood

eructation - forceful expulsion of gas from the stomach; also called belching

erythema - skin redness/inflammation usually caused by engorgement of the capillaries in the lower layers of skin

erythematosus - pertaining to redness or erythema

erythrocyte - red blood cell

erythropoiesis - formation of erythrocytes (red blood cells)

erythropoietin - a hormone formed from a plasma protein; it stimulates erythrocyte (red blood cell) production

esophagus - hollow muscular tube connecting the pharynx and the stomach

esophageal injury - Injury to the esophagus related to blunt external trauma is usually quite rare. Injury may be the result of rapid compression of the abdomen, which may raise pressures in the stomach to such a degree that an intraluminal tear of the esophagus results. Another mechanism is accelerated insufflation of pressured air into the esophagus in an attempt to ventilate the patient. Given the force of injury involved, other organs may be affected, particularly the trachea, which may also be ruptured.

Clinically, the patient may complain of chest or abdominal pain; later, signs of sepsis from contamination of the mediastinum and pleura may be present. Chest radiographs may show widening of the mediastinum, subcutaneous emphysema, pneumothorax, hydrothorax, or a combination. Usually the lower esophagus is affected; rupture is therefore into the left pleural cavity. Tube thoracostomy for drainage is often performed. If the output is suggestive of gastric contents or the injury is otherwise clinically suspected, a contrast study or endoscopy of the upper GI tract is indicated to evaluate the patient for esophageal injury. Treatment is usually surgical and should be performed early to minimize contamination of mediastinum and pleura. Primary repair vs diversion will depend on the condition of the esophagus, degree of contamination present, and, in some cases, the length of time from injury to surgery.

estrogens - female sex hormones from the ovaries; they support development/maintenance of female reproductive structures and secondary sex characteristics, fluid and electrolyte balance, and protein anabolism; e.g., beta-estradiol, estrone, and estriol

etiology - the study of the causes of disease, including theories of origin & the organisms, if any, involved

euphoria - subjectively pleasant feeling of well-being marked by confidence and assurance

eupnea - normal quiet breathing

euthanasia - the practice of ending a life in case of incurable disease

eversion - the movement of the sole outward at the ankle joint

exacerbation - an increase in the severity of symptoms or of disease

excitability - the ability of muscle tissue to receive and respond to stimuli; the ability of nerve cells to respond to stimuli and to convert them into nerve impulses

excrement - material cast out from the body as waste, especially fecal matter

excretion - the process of eliminating waste products from a cell, tissue, or the entire body; also, the products excreted

exocrine gland - a gland that secretes substances into ducts that empty at covering or lining epithelium or directly onto a free surface

exocytosis - a process of discharging large cellular products; particles are enclosed by Golgi membranes when synthesized; vesicles pinch off from the Golgi complex & carry enclosed particles to the interior of the cell membrane; fusion occurs & contents are discharged

exogenous - originating outside an organ or part

exon - a region of DNA that codes for synthesis of a protein

exophthalmic goiter - autoimmune disease that may result in hypersecretion of thryoid hormones; it is characterized by protrusion of the eyeballs (exophthalmos) and an enlarged thyroid (goiter); also called Grave's disease

expiration - breathing out; expelling air out of the lungs into the atmosphere; also called exhalation

expiratory reserve volume - the volume of air in excess of tidal volume that can be exhaled forcibly; equal to about 1,200 ml

extensibility - ability of muscle tissue to be stretched when pulled

extension - increase in the angle between two bones; restoring a body part to its anatomical position after flexion

external auditory canal - curved tube in the temporal bone that leads to the middle ear; also called the external auditory meatus

external nares - the external nostrils; the openings into the nasal cavity on the exterior of the body

exteroceptor - a receptor adapted for the reception of stimuli from outside the body

extracorporeal - the circulation of blood outside the body

extravasation - escape of fluid, especially of blood, lymph, or serum, from a vessel into tissue spaces

extrinsic - of external origin

exudate - escaping fluid or semifluid material that oozes from a space; it may contain serum, pus, & cellular debris
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- F -

facilitated diffusion - diffusion in which a substance not soluble by itself in lipids is transported across a selectively permeable membrane by combining with a transporter (carrier) molecule

facilitation - process in which a nerve cell membrane is partially depolarized by a subliminal stimulus so that a subsequent subliminal stimulus can depolarize the membrane further to reach the threshold of nerve impulse initiation

facultative reabsorption - absorption of water from distal convoluted tubules and collecting tubules of nephrons in response to antidiuretic hormone (ADH)

falciform ligament - a sheet of parietal peritoneum between the two principal lobes of the liver; the ligamentum teres, or remnant of the umbilical vein, lies within its folds

falx cerebelli - a small triangular process of the dura mater attached to the occipital bone in the posterior cranial fossa and projecting inward between the cerebellar hemispheres

fascia - fibrous membrane covering, supporting, & separating muscles

fascicle - a small bundle or cluster, especially of nerve or muscle fibers (cells); also called a fasciculus (plural, fasciculi)

fasciculation - involuntary brief twitch of a muscle, visible under the skin and not associated with the movement of the affected muscle

fauces - the opening from the mouth into the pharynx

febrile - feverish; pertaining to a fever

feces - material discharged from the rectum and made up of bacteria, excretions, and food residue; also called stool

fenestration - surgical opening made into the labyrinth of the ear for some conditions of deafness

fertilization - penetration of a secondary oocyte by a spermatozoon and subsequent union of the nuclei of the cells

fetus - latter stages of the developing young of an animal; in humans, the developing organism in utero from the beginning of the third month to birth

fibrillation - involuntary brief twitch of a muscle; visible under the skin & not associated with movement of the affected muscle

fibrin - an insoluble protein that is essential to blood clotting; formed from fibrinogen by the action of thrombin

fibrinogen - a high-molecular-weight protein in the blood plasma that, by action of thrombin, is converted to fibrin

fibrinolysis - dissolution of a blood clot by action of a proteolytic enzyme that converts insoluble fibrin into a soluble substance

fibroblast - large, flat cell that forms collagenous and elastic fibers and intercellular substance of loose connnective tissue

fibrocyte - a mature fibroblast that no longer produces fibers or intercellular substance in connective tissue

fibromyalgia - groups of common nonarticular rheumatic disorders characterized by pain, tenderness, and stiffness of muscles, tendons, and surrounding tissues; examples include lumbago and charleyhorse

fibroplasia - period of scar tissue formation

fibrosis - abnormal formation of fibrous tissue

fibrous joint - a joint that allows little or no movement, such as a suture and a syndesmosis

filiform papilla - one of the conical projections that are distributed in parallel rows over the anterior two-thirds of the tongue and contain no taste buds

filtrate - fluid produced when blood is filtered by the endothelial-capsular membrane of the nephron; any material that has passed through a filter

filtration - passage of liquid through a filter or a membrane that acts like a filter

filum terminale - nonnervous fibrous tissue of the spinal cord; it extends inferiorly from the conus medullaris to the coccyx

fimbriae - fingerlike structures, especially the lateral ends of the uterine (Fallopian) tubes

fissure - a groove, fold, or slit that may be normal or abnormal

fistula - abnormal passage between two organs or between an organ cavity and the outside

flaccid - relaxed, flabby, or soft; lacking muscle tone

flagellum - hairlike, motile process on the extremity of a bacterium or protozoan; plural, flagella

flail chest - This is the result of an injury of the chest wall significant enough to include multiple ribs resulting in a "free-floating" portion of the chest wall. Three major pathophysiologic events occur because of this. The first is interruption of the normal negative intrathoracic pressure needed to effect spontaneous ventilation as a result of the paradoxical motion of the flail portion of the chest wall. The more significant injury, however, is usually underlying pulmonary contusion, which leads to hemorrhage and edema of the injured lung. Finally, the amount of associated pain will often result in splinting with subsequent hypoventilation. The immediate threat to life depends on the amount of chest wall involved and the extent of the contusion. Treatment is centered on an assessment of the degree of pulmonary insufficiency with ventilator support as indicated. Rarely is physical stabilization of the chest wall necessary.

flatus - air (gas) in the stomach or intestines, commonly used to denote the passage of gas rectally

flexion - folding movement in which there is a decrease in the angle between two bones

fluoroscope - an instrument for visual observation of the body by means of X-ray

follicle - a small secretory sac or cavity

fontanel - a membrane-covered spot where bone formation is not yet complete, especially between the cranial bones of an infant's skull

foramen - a passage or opening; a communication between two cavities of an organ or a hole in a bone for passage of vessels or nerves

foramen ovale - opening in the fetal heart in the septum between the right and left atria; hole in the greater wing of the sphenoid bone that transmits the mandibular branch of the trigeminal (V) nerve

fornix - an arch or fold; a tract in the brain made up of association fibers, connecting the hippocampus with the mamillary bodies; a recess around the cervix of the uterus where it protrudes into the vagina

fossa - a shallow depression or a furrow

fracture - any break in a bone

frenulum - small fold of mucous membrane that connects two parts and limits movement

fulminate - to occur suddenly with great intensity

fundus - that part of a hollow organ farthest from the opening or exit

fungiform papilla - a mushroomlike elevation on the upper surface of the tongue, appearing as a red dot; papillae contain taste buds

furuncle - a boil; a painful nodule caused by bacterial infection and inflammation of a hair follicle or sebaceous (oil) gland
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gamete - a male or female reproductive cell; the spermatozoon or ovum

ganglion - a group of nerve cell bodies that lie outside the central nervous system; plural, ganglia

gangrene - death and rotting of a considerable mass of tissue; it usually is caused by an interruption of blood supply, followed by bacterial invasion by members of the genusClostridium

gastroenterology - the medical specialty that deals with the structure, function, diagnosis, and treatment of diseases of the stomach and intestines

gastrointestinal (GI) tract - a continuous tube running through the ventral body cavity extending from the mouth to the anus; also called the alimentary canal

gastroscopy - diagnostic procedure in which the interior of the stomach is examined with a gastroscope to: detect lesions, biopsy lesions, stop bleeding, and remove foreign objects

gastrulation - the various movements of groups of cells that lead to the establishment of the primary germ layers in the embryo

gavage - feeding via a tube passed through the esophagus and into the stomach

gene - biological LETTER of heredity; an ultramicroscopic, self-reproducing DNA segment, located in a specific position on a particular chromosome

genital herpes - a sexually-transmitted disease caused by type II herpes simplex virus

genitalia - reproductive organs

genome - the complete gene complement of an organism

genotype - the total hereditary information carried by an individual; the genetic makeup of an organism

geriatrics - the branch of medicine devoted to the medical problems and care of elderly persons

germanitivum - the skin layers where new cells are germinated

germinal epithelium - a layer of epithelial cells that covers the ovaries and lines the seminiferous tubules of the testes

gestation - the period of intrauterine fetal development

giantism - condition caused by hyper-secretion of human growth hormone (hGH) during childhood, characterized by excessive bone growth and body size; also called gigantism

gingivae - gums; they cover the alveolar processes of the mandible and maxilla & extend slightly into each tooth socket

gingivitis - inflammation of the gums

glans penis - slightly enlarged region at the distal end of the penis

glaucoma - eye disorder in which there is increased intraocular pressure due to an excess of aqueous humor

glomerular capsule - double-walled globe at the proximal end of a nephron; it encloses the glomerulus; also called Bowman's capsule

glomerulonephritis - inflammation of the glomeruli of the kidney; it increases the permeability of the endothelial-capsular membrane and permits blood cells and proteins to enter the filtrate; also called Bright's disease

glomerulus - rounded mass of nerves or blood vessels, especially the microscopic tuft of capillaries surrounded by the glomerular (Bowman's) capsule of each kidney tubule

glottis - the vocal folds (true vocal cords) in the larynx and the space between them (rima glottidis)

glucagon - a hormone produced by the alpha cells of the pancreas; it increases the blood glucose level

glucocorticoids - a group of hormones of the adrenal cortex; they influence glucose metabolism and are anti-inflammatory

gluconeogenesis - conversion of a molecule other than a carbohydrate into glucose

glucose - a six-carbon sugar that also includes 12 hydrogen atoms and six oxygen atoms; the major energy source for body cells

glycogen - a highly branched polymer of glucose containing thousands of subLETTERs; it functions as a compact store of glucose molecules in liver and muscle fibers (cells)

glycogenesis - the process by which many molecules of glucose combine to form the polymer called glycogen

glycogenolysis - the process of converting glycogen to glucose

glycosuria - presence of glucose in the urine; may be temporary or pathological; also called glucosuria

gnostic - pertaining to the faculties of perceiving and recognizing

goiter - a chronic enlargement of the thyroid gland

Golgi complex - cytoplasmic organelle consisting of four to eight flattened channels, stacked on each other, with expanded areas at their ends; functions in packaging secreted proteins, in lipid secretion, and in carbohydrate synthesis

gomphosis - a fibrous joint in which a cone-shaped peg fits into a socket

gonad - an organ that produces both gametes and hormones; the ovary in the female and the testis in the male

gonadocorticoids - sex hormones secreted by the adrenal cortex

gonadotropic hormone - a pituitary hormone that regulates the functions of the gonads

gonorrhea - infectious, sexually-transmitted disease caused by the bacterium Neisseria gonorrhoeae and characterized by inflammation of the urogenital mucosa, discharge of pus, and painful urination

gout - hereditary condition associated with excessive uric acid in the blood; the acid crystallizes and deposits in joints, kidney, and soft tissues

gray ramus communicans - a short nerve containing postganglionic sympathetic fibers; the cell bodies of the fibers are in a sympathetic chain ganglion, and the nonmyelinated axons run by way of the gray ramus to a spinal nerve and then to the periphery to supply effectors

greater omentum - large fold in the serosa of the stomach; it hangs down like an apron over the front of the intestines

groin - the depression between the thigh and the trunk; the inguinal region

gustatory - pertaining to taste

gynecology - a branch of medicine dealing with study and treatment of disorders of the female reproductive system

gynecomastia - excessive growth (benign) of male mammary glands due to secretion of estrogens by an adrenal gland tumor (feminizing adenoma)

gyrus - one of the folds of the cerebral cortex of the brain; plural, gyri; also called a convolution

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h.c. somatomammotropin - hCS; a hormone produced by the chorion of the placenta that may stimulate breast tissue for lactation

h. chorionic gonadotropin - hCG; a hormone produced by the chorion of the placenta; it maintains the corpus luteum

Haldane effect - decreased carbon dioxide binding in the blood as a result of increased oxygen-hemoglobin binding; oxyhemoglobin is more acidic than unbound hemoglobin and, therefore, combines with less carbon dioxide

hallucination - the sensory perception of something that does not really exist in the world; a sensory experience created from within the brain

haploid - having half the number of chromosomes normally found in the somatic cells of an organism; characteristic of mature gametes

haustra - the sacculated elevations of the colon

Haversian system - the basic structural LETTER in adult compact bone, consisting of a central (Haversian) canal with concentrically arranged lamellae, lacunae, osteocytes, and canaliculi; also called an osteon

heart murmur - one of a number of abnormal heart sounds; consists of a flow noise that is heard before the normal lubb-dupp or that may mask normal heart sounds

hematocrit (Hct) - percentage of blood made up of red blood cells; usually calculated by centrifuging a blood sample in a graduated tube & reading off the volume of red blood cells and total blood

hematology - the study of blood

hematopoiesis - blood cell production occurring in the red bone marrow; also called hemopoiesis

hematuria - blood in the urine

hemiballismus - violent muscular restlessness of half of the body, especially of the upper extremity

hemiplegia - a paralysis of the upper extremity, trunk, and lower extremity on one side of the body

hemocytoblast - immature stem cell in bone marrow; it develops along different lines into all the types of mature blood cells

hemodialysis - filtering blood while it is circulated outside the body by means of an artificial device; substances are removed as a result of their different rates of diffusion through a selectively permeable membrane

hemodynamics - study of factors and forces that govern the flow of blood through blood vessels

hemoglobin - molecule in red blood cells consisting of the protein globin and the iron-containing red pigment heme and constituting about 33% of the cells' volume; it is involved in the transport of oxygen and carbon dioxide

hemolysis - escape of hemoglobin from the interior of red blood cells into the surrounding medium; results from disruption of the integrity of the cell membrane by toxins or drugs, by freezing or thawing, or by hypotonic solutions

hemolytic disease - a hemolytic anemia of a newborn child; it results from the destruction of the infant's red blood cells by antibodies produced by the mother; usually involves antibodies due to Rh blood type incompatibility; also called erythroblastosis fetalis

hemophilia - a hereditary blood disorder where there is a deficient production of certain factors involved in blood clotting, resulting in excessive bleeding into joints, deep tissues, and elsewhere

hemopoiesis - blood cell production occurring in the red marrow of bones; also called hematopoiesis

hemoptysis - spitting of blood from the respiratory tract

hemorrhage - bleeding; escape of blood from blood vessels, especially when it is profuse

hemorrhoids - dilated or varicosed blood vessels (usually veins) in the anal region; also called piles

hemostasis - the stoppage of bleeding

hemothorax - Blood from a variety of sources may accumulate in the pleural space. In most cases, the volume is too small to be hemodynamically significant in terms of volume loss or compression of the lung or mediastinum. Still, evacuation via tube thoracostomy is generally recommended. This allows the physician to detect any persistent bleeding into the pleural space and prevents the organization of the hemothorax, which can later progress to a fibrothorax with resultant lung entrapment.

hepatic - referring to the liver

hepatitis - inflammation of the liver due to an infectious agent, drugs, or chemicals

hepatopancreatic ampulla - a small, raised area in the duodenum where the combined common bile duct and main pancreatic duct empty into the duodenum; also called the ampulla of Vater

hernia - protrusion or projection of an organ or part of an organ through a membrane or a cavity wall, usually the abdominal cavity

herniated disc - rupture of intervertebral disc so that the nucleus pulposus protrudes into the vertebral cavity; also called a slipped disc

heterocrine gland - any gland, such as the pancreas, which is both endocrine and exocrine

heterozygous - possessing a pair of different genes on homologous chromosomes for a particular hereditary characteristic

hiatus - an opening; a foramen

hilus - an area, depression, or pit where blood vessels and nerves enter or leave an organ; also called a hilum

hirsutism - excessive growth of hair in females and children, due to the conversion of vellus hairs into large terminal hairs; occurs in response to higher-than-normal levels of androgens; the distribution is similar to that in adult males

histamine - a substance found in many cells, particularly mast cells, basophils, and platelets, and released when the cells are injured; results in vasodilation, increased permeability of blood vessels,and bronchiole constriction

histocompatibility testing - comparison of human leucocyte associated (HLA) antigens between donor and recipient to determine the degree of compatibility between the two; also called HLA antigen typing or tissue typing

histology - microscopic study of the structure of tissues

hives - skin condition marked by reddened elevated patches that are often itchy; may be caused by infections, trauma, medications, emotional stress, certain foods or food additives

holocrine gland - type of gland in which the entire secreting cell, containing its accumulated secretions, is included in the secretory product of the gland, as in the sebaceous or oil glands

homeostasis - the condition in which the body's internal environment remains relatively constant, within physiological limits

homologous - a correspondence of two organs in structure, position, and origin

hormone - a secretion of an endocrine gland; it alters the physiological activity of target cells in the body

humoral immunity - the component of immunity in which lymphocytes (B cells) develop into plasma cells that produce antibodies to destroy antigens; also called antibody-mediated immunity

hyaline membrane disease - a disease of newborn infants, especially those who are premature, in which insufficient amounts of surfactant are produced and breathing is labored; also called respiratory distress syndrome (RDS) of the newborn

hyaluronic acid - viscous, amorphous extra-cellular material; it binds cells together, lubricates joints, and maintains the shape of the eyeballs

hyaluronidase - enzyme that breaks down hyaluronic acid, increasing the permeability of connective tissues by dissolving the substances that hold body cells together

hydrocele - a fluid-containing sac or tumor; specifically, a collection of fluid formed in the space along the spermatic cord and in the scrotum

hydrocephalus - abnormal accumulation of cerebrospinal fluid on the brain

hydrophobia - rabies; a condition characterized by severe muscle spasms when attempting to drink water; also, an abnormal fear of water

hymen - a thin fold of vascularized mucous membrane at the vaginal orifice

hyperbaric oxygenation - using a hyperbaric chamber to raise oxygen levels in blood to treat anaerobic (tetanus and gangrene) bacterial infections; also used to treat carbon monoxide poisoning

hypercalcemia - an excess of calcium in the blood

hypercapnia - an abnormal increase in the amount of carbon dioxide in the blood

hyperemia - an excess of blood in an area or part of the body

hyperextension - continuation of extension beyond the anatomical position, as in bending the head backward

hyperglycemia - elevated blood sugar level

hypermetropia - condition in which visual images are focused behind the retina with resulting defective vision of near objects; farsightedness

hyperphosphatemia - an abnormally high level of phosphate in the blood

hyperplasia - an abnormal increase in the numer of normal cells in a tissue or organ, increasing its size

hyperpolarization - increase in the internal negativity across a cell membrane, thus increasing the voltage and moving it farther away from the threshold value

hypersecretion - overactivity of glands resulting in excessive secretion

hypersensitivity - overreaction to an allergen, leading to pathological changes in tissues; also called allergy

hypertension - high blood pressure

hyperthermia - elevated body temperature

hypertonia - increased muscle tone that is expressed as spasticity or rigidity

hypertonic - having an osmotic pressure greater than that of the solution with which it is compared

hypertrophy - excessive enlargement or overgrowth of tissue without cell division

hyperventilation - a rate of respiration higher than that required to maintain normal level of plasma PCO2

hypervitaminosis - an excess of one or more vitamins

hypocalcemia - lower than normal levels of calcium in the blood

hypochloremia - deficiency of chloride in the blood

hypoglycemia - abnormally low concentration of blood glucose; can result from excess insulin (injected or secreted)

hypokalemia - deficiency of potassium in the blood

hypomagnesemia - deficiency of magnesium in the blood

hyponatremia - deficiency of sodium in the blood

hyponychium - the epithelium of the nail bed, particularly the posterior part

hypophosphatemia - an abnormally low level of phosphate in the blood

hypophyseal pouch - a fold of ectoderm in the stomodeal (mouth) roof, from which the adenohypophysis (anterior lobe) of the pituitary gland develops embryologically

hypophysis - pituitary gland

hypoplasia - defective (decreased) tissue development

hyposecretion - underactivity of glands resulting in decreased secretion

hypospadias - displaced urethral opening; in the male, it may be on the underside of the penis, at the penoscrotal junction, between the scrotal folds, or in the perineum; in the female, the urethra opens into the vagina

hypothalamic-hypophyseal tract - a bundle of nerve processes made up of fibers that have cell bodies in the hypothalamus but release neurosecretions in the posterior pituitary gland or neurohypophysis

hypothalamus - portion of the diencephalon that lies beneath the thalamus and forms the floor and part of the wall of the third ventricle

hypothermia - lowering body temperature below 35 C (95 F) degrees; in surgical procedures, it refers to deliberate cooling of the body to slow metabolism and reduce tissue oxygen needs

hypotonia - state of decreased or lost muscle tone in which muscles appear flaccid

hypotonic - having an osmotic pressure lower than that of another solution with which it is compared

hypoventilation - a rate of respiration lower than that required to maintain the normal level of plasma PCO2

hypovolemic shock - shock characterized by decreased intravascular volume resulting from blood loss; may occur because of acute hemorrhage or other excessive fluid loss

hypoxia - lack of adequate oxygen at the tissue level

hysterectomy - the surgical removal of the uterus
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ileocecal sphincter - a fold of mucous membrane that guards the opening from the ileum into the large intestine; also called ileocecal valve

ileum - the terminal portion of the small intestine

immunity - state of being resistant to injury, particularly by poisons, foreign proteins, and invading parasites, due to the presence of antibodies

immunogenicity - the ability of an antigen to stimulate antibody production

immunoglobulin (Ig) - an antibody synthesized by plasma cells (derived from B lymphocytes) in response to the introduction of antigen; immunoglobulins are divided into 5 kinds (IgG, IgM, IgA, IgD, IgE), based primarily on the larger protein component present in the immunoglobulin

immunology - a branch of science dealing with the responses of the body when it is challenged by antigens

immunosuppression - inhibition of the immune response

immunotherapy - an attempt to induce the immune system to mount an attack against cancer cells by administration of antibodies or nonspecific immune stimulants

imperforate - abnormally closed

impetigo - a contagious skin disorder characterized by pustular eruptions

implantation - insertion of a tissue or a part into the body; attachment of the blastocyst to the lining of the uterus 7-8 days after fertilization

impotence - weakness; inability to copulate; failure to maintain an erection long enough for sexual intercourse

in utero - within the uterus

in vitro - literally, in glass; outside the living body and in an artificial environment such as a laboratory test tube

in vivo - in the living body

incontinence - inability to retain urine, semen, or feces, through loss of sphincter control

infarction - the presence of a localized area of necrotic tissue, produced by inadequate oxygenation of the tissue

infection - invasion and multiplication of microorganisms in body tissues; may be inapparent or be characterized by cellular injury

infectious mononucleosis - contagious disease caused by the Epstein-Barr virus (EBV) and characterized by elevated mononucleocyte and lymphocyte counts, fever, sore throat, stiff neck, cough, and malaise

inferior vena cava (IVC) - the large vein that collects blood from those parts of the body inferior to the heart and returns it to the right atrium

inflammation - a localized, protective response to tissue injury designed to destroy, dilute, or wall off the infecting agent or injured tissue; characterized by redness, pain, heat, swelling, and occasional loss of function

inflammatory bowel d. - 1) Crohn's disease (GI tract inflammation, especially the distal ileum/proximal colon, which may extend from the mucosa through the serosa) or 2) ulcerative colitis (GI tract inflammation, usually limited to the large intestine and accompanied by rectal bleeding)

infraspinous - below a spine; specifically the fossa located beneath the scapular spine

infundibulum - the stalk-like structure that attaches the pituitary gland (hypophysis) to the hypothalamus of the brain; the funnel-shaped, open, distal end of the uterine (Fallopian) tube

ingestion - taking in of food, liquids, or drugs, by mouth

inguinal - pertaining to the groin

inorganic compound - any compound that usually lacks carbon, is usually small, and contains ionic bonds; examples include water as well as many acids, bases, and salts

insertion - manner or place of attachment of a muscle to the bone(s) that it moves

insomnia - difficulty falling asleep as well as, usually, frequent awakening

inspiration - the act of drawing air into the lungs

insula - triangular area of cerebral cortex that lies deep within the lateral cerebral fissure, under the parietal, frontal, & temporal lobes: it cannot be seen in an external view of the brain; also called the island or isle of Reil

insulin - a hormone produced by the beta cells of the pancreas; it decreases the blood glucose level

integrin - the receptor on a plasma membrane that interacts with an adhesion protein found in intercellular material and in blood

integumentary - relating to the skin

intercalated disc - irregular transverse thickening of sarcolemma that contains: 1) desmosomes holding the cardiac muscle fibers (cells) together and 2) gap junctions that aid in the conduction of muscle action potentials

intercostal nerve - a nerve supplying a muscle located between the ribs

interferon (IFN) - one of the proteins (alpha, beta, gamma), naturally produced by virus-infected cells; it induces uninfected cells to synthesize antiviral proteins that inhibit intracellular viral replication in uninfected cells; synthesized artificially via recombinant DNA methods

interphase - the period of the cell's life cycle during which all processes except division are occuring; period between two mitotic divisions; also called metabolic phase

interstitial endocrinocyte - cell located in the connective tissue between semi-niferous tubules in mature testis; secretes testosterone; also called an interstitial cell of Leydig

interventricular foramen - the narrow, oval opening through which the lateral ventricles of the brain commmunicate with the third ventricle; also called the foramen of Monro

intervertebral disc - the pad of fibrocartilage located between the bodies of two adjacent vertebrae

intracellular fluid (ICF) - fluid located within cells

intrafusal fibers - three to ten specialized muscle fibers (cells), enclosed partly by a connective tissue capsule that is filled with lymph; these fibers compose the muscle spindles

intramembranous ossif.... - method of bone formation in which bone is formed directly in membranous tissue

intraocular pressure (IOP) - the pressure in the eyeball, produced mainly by aqueous humor

intrinsic - of internal origin; e.g., the intrinsic factor, a muco-protein that is formed by gastric mucosa and is necessary for the absorption of vitamin B12

intron - region of DNA that does not code for the synthesis of a protein

intubation - insertion of a tube through the nose or mouth into the larynx and trachea to allow entrance of air or to dilate a stricture

intussesception - the infolding (invagination) of one part of the intestine within another segment

invagination - an infolding of the wall of a cavity into the cavity itself

inversion - the movement of the sole inward at the ankle joint

ion - a charged particle or group of particles; formed usually when a substance, such as salt, dissolves and dissociates

ipsilateral - on the same side; affecting the same side of the body

irritable bowel syndrome - stress-induced disease of the GI tract; cramping and pain accompany alternating diarrhea and constipation; stool may contain excess mucus; flatulence, nausea, and loss of appetite may occur; also called irritable colon or spastic colon

ischemia - the lack of sufficient blood to a part due to obstruction of circulation

isotonic - having equal tension or tone; having equal osmotic pressure between two different solutions or two elements in a solution

isotope - chemical element that has the same atomic number as another but has a different atomic weight; radioactive isotopes change into other elements with emission of certain types of radiation

isovolumetric contraction - the period of time, about 0.05 sec, between the start of ventricular systole and opening of the semilunar valves; there is ventricular contraction, but no emptying, & there is a rapid rise in ventricular pressure

isthmus - a narrow strip of tissue or narrow passage connecting two larger parts
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jaundice - condition characterized by yellowness in skin, whites of the eyes, mucous membranes, and body fluids; results from buildup of bilirubin

jejunum - the middle portion of the small intestine

joint kinesthetic receptor - a proprioceptive receptor located in a joint, stimulated by joint movement

juxtaglomerular apparatus (JGA) - the macula densa (distal tubule cells adjacent to an afferent and efferent arteriole) & juxtaglomerular cells (modified cells of the afferent &, sometimes, efferent arteriole); secretes renin when blood pressure starts to fall
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karyotype - an arrangement of chromosomes by shape, size, and position of centromeres

keratin - an insoluble protein found in the hair, nails, and other keratinized tissues of the epidermis

keratinocyte - the most numerous of the epidermal cells that function in keratin production

keratohyalin - a compound involved in the formation of keratin

keratosis - formation of a hardened growth of tissue

ketone bodies - substances such as acetone, acetoacetic acid, and beta-hydroxybutyric acid, produced primarily during excessive fat metabolism

ketosis - abnormal condition marked by excessive production of ketone bodies

kidney - one of the paired reddish organs located in the lumbar region; they regulate composition and volume of blood and produce urine

kilocalorie (kcal) - amount of heat required to raise the temperature of 1000 grams of water 1 C degree; the LETTER used to express the heating value of foods and to measure metabolic rate

kinesiology - the study of movement of body parts

kinesthesia - ability to perceive extent, direction, or weight of movement; muscle sense

Korotkoff sounds - the various sounds that are heard while taking blood pressure

kyphosis - exaggeration of the thoracic curve of the vertebral column, leading to a round-shouldered or hunchback appearance
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labia majora - two longitudinal folds of skin extending downward and backward from the mons pubis of the female

labia minora - two small folds of mucous membrane lying medial to the labia majora of the female

labial frenulum - the medial fold of mucous membrane between the inner surface of the lip and the gums

labium - a lip; a liplike structure; plural, labia

labyrinth - an intricate communicating passageway, especially in the internal ear

labyrinthine disease - malfunction of the internal ear characterized by deafness, tinnitus, vertigo, nausea, and vomiting

laceration - wound or irregular area of the skin

lacrimal - pertaining to tears

lactation - the secretion and ejection of milk by the mammary glands

lacteal - one of many lymphatic vessels in the intestinal villi; they absorb fat molecules from digested food

lacuna - a small, hollow space, such as those in which the osteoblasts lie within bones; plural, lacunae

lambdoidal suture - the line of union between the parietal bones and the occipital bone in the skull; sometimes contains sutural (Wormian) bones

lamellae - concentric rings found in compact bone

lamina - a thin, flattened layer or membrane, as the flattened part on either side of the arch of a vertebra; plural, laminae

lamina propria - the connective tissue layer of a mucous membrane

lanugo - fine downy hairs that cover the fetus

laparoscopy - insertion of a laparoscope through an abdominal incision to: view abdominal and pelvic viscera, remove fluids or tissues for biopsy, drain ovarian cysts, cut adhesions, stop bleeding, and perform tubal ligation

laryngitis - an inflammation of the mucous membrane lining the larynx

laryngopharynx - the inferior portion of the pharynx, extending downward from the level of the hyoid bone to divide posteriorly into the esophagus & anteriorly into the larynx

laryngoscope - instrument for examining the larynx

laryngotracheal bud - outgrowth of foregut endoderm from which the respiratory system develops

larynx - the voice box, a short passageway that connects the pharynx with the trachea

lateral - farther from the midline of the body or a structure

lesion - any localized, abnormal change in tissue formation

lesser omentum - the fold of peritoneum that extends from the liver to the lesser curvature of the stomach & the commencement of the duodenum

lethargy - a condition of drowsiness or indifference

leukemia - a malignant disease of the blood-forming tissues with acute overproduction and accumulation of immature leucocytes, many of which fail to reach maturity, or with chronic accumulation of mature lymphocytes because they do not die at the end of a normal lifespan

leukocyte - a white blood cell

leukocytosis - an increase in the number of white blood cells, characteristic of many infections and other disorders

leukopenia - a decrease in the number of white blood cells below 5,000 per cubic millimeter

leukoplakia - a disorder in which there are white patches in the mucous membranes of the tongue, gums, and cheeks

libido - the sexual drive, conscious or unconscious

ligament - dense, regularly-arranged connective tissue attaching bone to bone

ligand - a chemical in interstitial fluid, usually in a concentration lower than that in cells

lingual frenulum - a fold of mucous membrane that connects the tongue to the floor of the mouth

lipase - a fat-splitting enzyme

lipogenesis - synthesis of lipids from glucose or amino acids by the cells in the liver

lipoma - a fatty tissue tumor, usually benign

lipoprotein - a protein containing lipid; some made in the liver bind cholesterol & triglycerides to raise their solubility in blood; high levels of LDL's (low-density) are risk factors for atherosclerosis & high levels of HDL's (high-density) are protective against it

lithotripsy - a noninvasive procedure in which shock waves generated by an instrument called a lithotriptor are used to pulverize kidney stones or gallstones

lobe - any curved or rounded projection of a structure

locus coeruleus - a cluster of neurons in the brain stem where norepinephrine (NE) is concentrated

lordosis - exaggeration of the lumbar curve of the vertebral column

lumbar - region of the back and side between the ribs and pelvis; loin

lumen - the space within a tubular structure such as a blood vessel or the intestine

lunula - the moon-shaped, white area at the base of a nail

luteinizing hormone (LH) - adenohypophysal hormone which, in females, stimulates ovulation and progesterone secretion by the corpus luteum and readies the mammary glands for milk production; in males, it stimulates testosterone secretion by the testes

lymph - fluid confined in lymphatic vessels & flowing through the lymphatic system to be returned to the blood

lymphangiography - a procedure in which lymphatic vessels and lymph organs are filled with a radiopaque substance to be X-rayed

lymphatic vessel - a large vessel that collects lymph from lymph capillaries & converges with other lymphatic vessels to form the thoracic and right lymphatic ducts

lymphocyte - a type of white blood cell, found in lymph nodes, associated with the immune system

lymphokines - powerful proteins secreted by T lymphocytes; they stimulate the various activities of B and T cells in immune responses

lysosome - organelle in the cytoplasm of a cell, enclosed by a single membrane and containing powerful digestive enzymes

lysozyme - bactericidal enzyme found in tears, saliva, and perspiration
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macrophage - a phagocytic cell derived from a monocyte; may be fixed or wandering

macula - discolored spot or colored area; a small, thickened region on the wall of the utricle and saccule, that serves as a receptor for static equilibrium

macula lutea - a yellow spot in the center of the retina

malaise - discomfort, uneasiness, & indisposition, often indicative of infection

malignant - referring to diseases that tend to become worse and cause death, especially the invasion and spreading of cancer

malignant melanoma - a usually dark, malignant tumor of the skin; contains melanin

malnutrition - state of poor nutrition that may be due to inadequate food intake, imbalance of nutrients, malabsoption of nutrients, inappropriate distribution of nutrients, increased nutrient requirements, increased nutrient losses, or overnutrition

mammary gland - a modified sudoriferous (sweat) gland of the female; it secretes milk for nourishment of the young

mammillary bodies - two small rounded bodies posterior to the tuber cinereum, involved in reflexes related to the sense of smell

mammography - procedure for imaging the breasts (xeromammography or film-screen mammography) to evaluate for breast disease or to screen for breast cancer

Marfan syndrome - inherited disorder that results in connective tissue abnormalities, especially in the skeleton, eyes, and cardiovascular system

marrow - soft, spongelike material in the cavities within bone; red marrow produces blood cells; yellow marrow is formed mainly of fatty tissue and has no blood-producing function

massive hemothorax - Large amounts of blood accumulated within the pleural cavity will cause hypovolemia and hypotension. Sources of bleeding may include lung parenchyma, great vessels, or chest wall vessels such as the intercostal artery. The presentation is shock associated with absent breath sounds on the affected side(s). Dullness to percussion may also be present, although this finding is difficult to elicit in most resuscitation settings. Treatment consists of rapid evacuation with large pleural chest tubes. Once the initial accumulation of blood is evacuated, continued blood output from the chest tube is monitored. The most important treatment during the resuscitative period is rapid volume replacement. Definitive therapy requiring thoracotomy is usually undertaken if the rate of chest tube output is > 100 mL every 30 min. Usually this is performed by a trauma or thoracic surgeon under controlled conditions in the operating room.

mastectomy - surgical removal of breast tissue

mastication - chewing

meatus - a passage or opening, especially in the external portion of a canal

mechanoreceptor - receptor that detects mechanical deformation of the receptor itself or adjacent cells; stimuli so detected include those related to touch, pressure, vibration, proprioception, hearing, equilibrium, and blood pressure

medial - nearer the midline of the body or a structure

medial lemniscus - a flat band of myelinated nerve fibers that extends through the medulla, pons, and midbrain; it terminates on the same side in the thalamus; sensory neurons in this tract transmit impulses for proprioception, fine touch, pressure, and vibration sensations

median aperture - one of the three openings in the roof of the fourth ventricle through which cerebrospinal fluid enters the subarachnoid space of the brain and spinal cord; also called the foramen of Magendie

mediastinum - a broad, median partition, actually a mass of tissue found between the pleurae of the lungs; it extends from the sternum to the vertebral column

medulla - an inner layer of an organ, such as the medulla of the kidneys

medulla oblongata - the most inferior part of the brain stem

medullary cavity - space within the diaphysis of a mature bone; it contains yellow marrow; also called the marrow cavity

medullary rhythmicity area - portion of the respiratory center in the medulla that controls the basic rhythm of respiration

meiosis - the type of cell division restricted to sex-cell production; involving two successive nuclear divisions, it results in daughter cells with the haploid (n) number of chromosomes

melanin - a dark (black, brown, or yellow) pigment found in some parts of the body, such as the skin

melanoblast - a precursor cell in the epidermis that gives rise to melanocytes, cells that produce melanin

melanocyte - a pigmented cell located between or beneath cells of the deepest layer of the epidermis; synthesizes melanin

melatonin - a hormone secreted by the pineal gland; may inhibit reproductive activities

membranous labyrinth - portion of the labyrinth of the inner ear that is located inside the bony labyrinth and separated from it by the perilymph; made up of the membranous semi-circular canals, the saccule and utricle, and the cochlear duct

menarche - beginning of the menstrual cycles

Meniere's syndrome - a type of labyrinthine disease characterized by fluctuating loss of hearing, vertigo, and tinnitus; due to an increased amount of endolymph that enlarges the labyrinth

meninges - three membranes covering the brain and spinal cord; include the dura mater, the arachnoid, and the pia mater; singular, meninx

meningitis - an inflammation of the meninges, most commonly the pia mater & the arachnoid

menopause - termination of menstrual cycles

menstrual cycle - a series of changes in the endometrium of a nonpregnant female; with each cycle, the lining is thickened and matured and is capable of supporting development of a fertilized ovum

menstruation - the periodic discharge of blood, tissue fluid, mucus, and epithelial cells form the uterus; it usually lasts for 5 days; it is caused by a sudden reduction in the levels of estrogens and progesterone; also called the menstrual phase or menses

merocrine gland - secretory cell that remains intact throughout the process of formation and discharge of the secretory products; e.g., the salivary and pancreatic glands

mesenchyme - an embryonic connective tissue from which all other connective tissues arise

mesentery - fold of peritoneum attaching the small intestine to the posterior abdominal wall

mesocolon - fold of peritoneum attaching the colon to the posterior abdominal wall

mesothelium - a layer of simple squamous epithelium that lines serous cavities

mesovarium - a short fold of peritoneum that attaches an ovary to the broad ligament of the uterus

metabolism - the sum total of all bio-chemical reactions that occur within an organism, including synthetic (anabolic) reactions as well as decomposition (catabolic) reactions

metacarpus - a collective term for the five bones making up the palm of the hand

metaphase - second stage of mitosis in which chromatid pairs line up on the equatorial plane of the cell

metaphysis - growing portion of a bone

metaplasia - the transformation of one cell into another

metarteriole - blood vessel that emerges from an arteriole, traverses a capillary network, and empties into a venule

metastasis - the spread of cancer to the surrounding tissues (local) or to other body sites (distant)

metatarsus - a collective term for the five bones located in the foot between the tarsals and the phalanges

micelle - spherical aggregate of bile salts that dissolves fatty acids and monoglycerides so that they can be transported into small intestinal epithelial cells

microcephalus - an abnormally small head; premature closing of the anterior fontanel so that the brain has insufficient room for growth, resulting in mental retardation

microfilament - rodlike cytoplasmic structure about 6nm in diameter; composes contractile LETTERs in muscle fibers (cells) and provides support, shape, and movement in nonmuscle cells

microglia - neuroglial cells that carry on phagocytosis; also called brain macrophages

microphage - any granular leucocyte that carries on phagocytosis, especially neutrophils and eosinophils

microtomography - a procedure that combines the principles of electron microscopy and computed tomography to produce highly magnified, three-dimensional images of living cells

microtrabeculae - three-dimensional mesh-work of fine filaments, ca. 10-15 nm in diameter, that hold together microfilaments, microtubules, and intermediate filaments constituting the microtrabecular lattice

microtubule - a cylindrical cytoplasmic structure, ranging in diameter from 18-30 nm and consisting of the protein tubulin; provides support, structure, and transportation

microvilli - the microscopic, fingerlike projections of cell membranes of small intestinal cells; they increase surface area for absorption

micturition - the act of expelling urine from the urinary bladder; also called urination

mineralocorticoids - a group of hormones of the adrenal cortex; they affect mineral and water balance

mitochondrion - a double-membrane bounded organelle that plays a central role in production of ATP; known as the powerhouse of the cell

mitosis - division of the cell nucleus involving distribution of two sets of replicated chromosomes into separate nuclei; ensures that each daughter nucleus has the same number and kind of chromosomes as the original parent nucleus

mitral stenosis - a narrowing of the mitral valve by scar formation or a congenital defect

Mittelschmerz - abdominopelvic pain that correlates with the time of release of a secondary oocyte from the ovary

modality - any of the specific sensory entities, such as vision, smell, or taste

modiolus - central pillar or column of the cochlea

molecule - the chemical combination of two or more atoms

monocyte - a type of white blood cell characterized by agranular cytoplasm; the largest of the leucocytes

mons pubis - the rounded, fatty prominence over the symphysis pubis, covered by coarse pubic hair

morbid - diseased; pertaining to disease

morula - a solid mass of cells produced by successive cleavages of a fertilized ovum a few days after fertilization

mucin - a protein found in mucus

mucosa - a membrane that lines a body cavity opening to the exterior; also called mucous membrane

mucous cell - a unicellular gland that secretes mucus; also called a goblet cell

multiple sclerosis - progressive destruction of myelin sheaths of neurons in the central nervous system, short-circuiting conduction pathways

muscarinic receptor - a receptor found on all effectors innervated by parasympathetic (& on some innervated by sympathetic) postganglionic axons; so named because the actions of acetylcholine (Ach) on such receptors are similar to those produced by application of muscarine

muscular dystrophies - several inherited muscle-destroying diseases, characterized by degeneration of the individual muscle fibers (cells), which leads to progressive atrophy of the skeletal muscle

muscularis - a muscular layer (coat or tunic) of an organ

muscularis mucosae - a thin layer of smooth muscle fibers (cells) located in the outermost layer of the mucosa of the gastrointestinal tract underlying the lamina propria of the mucosa

mutation - any chage in the sequence of bases in the DNA molecule resulting in a permanent alteration in some heritable characteristic

myasthenia gravis - weakness of skeletal muscles caused by antibodies directed against acetylcholine receptors; results in inhibition of muscle contraction

myelin sheath - a white, phospholipid, segmented covering, formed by neurolemmocytes (Schwann cells), around the axons and the dendrites of many peripheral neurons

myelography - introduction of a contrast medium into the subarachnoid space of the spinal cord to demonstrate tumors or herniated (slipped) discs within or near the spinal cord

myocardial contusion - Myocardial contusion is usually a result of blunt blows to the anterior portion of the chest, and there is potential for injury to the underlying myocardium. The diagnosis of myocardial contusion can often be problematic. The clinician should focus on the clinical picture, which will depend largely on the type and extent of injury. Major sequelae include regional wall motion abnormalities and depressed cardiac function not unlike that seen with myocardial infarction. Injured areas may also serve as a nidus for rhythm disturbances. A pericardial effusion may occur, as can early or late pericarditis. In more severe cases, intracardiac injury such as ventricular or valvar rupture may be seen. Rather than relying on rigid criteria, the diagnosis hinges on a strong index of suspicion and specific tests for the potential sequelae: monitoring the ECG for the presence of arrhythmias; measuring cardiac enzymes, which may demonstrate myocardial injury; and using ultrasound to detect any wall motion abnormalities or intracardiac injury. Accumulation of pericardial fluid may also be assessed by echocardiography.  Treatment is based on the findings. In most cases, therapy is supportive and is often analogous to management after myocardial infarction.

myocardial infarction - gross necrosis of myocardial tissue due to interrupted blood supply; also called a heart attack

myocardium - the middle layer of the heart wall, made up of cardiac muscle, composing the bulk of the heart, and lying between the epicardium and the endocardium

myofibril - threadlike structure, running longitudinally through a muscle fiber (cell) and consisting mainly of thick myofilaments (myosin) and thin myofilaments (actin, troponin, tropomyosin)

myoglobin - the oxygen-binding conjugated protein present in the sarcoplasm of muscle fibers (cells); contributes the red color to muscle

myogram - the record or tracing produced by a myograph, the apparatus that measures and records the effects of muscular contractions

myology - the study of muscles

myometrium - the smooth muscle layer of the uterus

myopia - defect in vision so that objects can be seen clearly only when very close to the eyes; nearsightedness

myosin - the contractile protein making up the thick myofilaments of muscle fibers (cells)

myotonia - continuous muscle spasm; increased muscular irritability and tendency to contract, and lessened ability to relax

myxedema - condition caused by hypothyroidism during the adult years, characterized by swelling of facial tissues
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nail matrix - the part of the nail beneath the body and root from which the nail is produced

narcosis - an unconscious state due to physical or chemical factors that depress neuronal excitability

nasal septum - vertical partition separating the nasal cavity into left and right sides; of bone (perpendicular plate of ethmoid and vomer) and cartilage, covered with a mucous membrane

nasolacrimal duct - a canal that transports the lacrimal secretion (tears) from the nasolacrimal sac into the nose

nasopharynx - the uppermost portion of the pharynx, lying posterior to the nose & extending down to the soft palate

nausea - discomfort characterized by loss of appetite and sensation of impending vomiting

nebulization - administration of medication to selected portions of the respiratory tract by droplets suspended in air

necrosis - death of a cell or group of cells as a result of disease or injury

neonatal - pertaining to the first 4 weeks after birth

neoplasm - a new growth that may be benign or malignant

nephritis - inflammation of the kidney

nephron - the functional LETTER of the kidney

nephrotic syndrome - a condition in which the endothelial-capsular membrane leaks, allowing large amounts of protein to escape into the urine

neuralgia - attacks of pain along the entire course or branch of a peripheral sensory nerve

neuritis - an inflammation of a single nerve, two or more nerves in separate areas, or many nerves simultaneously

neuroeffector junction - collective term for neuromuscular and neuroglandular junctions

neurofibral node - a space (along a myelinated nerve fiber) between the individual neurolemmocytes (Schwann cells) that form the myelin sheath; also called the node of Ranvier

neurofibril - one of the delicate threads that forms a complicated network in the cytoplasm of the cell body and processes of a neuron

neuroglandular junction - area of contact between a motor neuron and a gland

neuroglia - nervous system cells specialized to perform connective tissue functions; in the CNS, include astrocytes, oligodendrocytes, microglia, & ependyma; in the PNS, include neurolemmocytes (Schwann cells) & ganglion satellite cells; also called glial cells

neurohypophyseal bud - an outgrowth of ectoderm located on the floor of the embryonic hypothalamus; it gives rise to the neurohypophysis (posterior lobe) of the pituitary gland

neurohypophysis - the posterior lobe of the pituitary gland

neurolemma - the peripheral, nucleated cytoplasmic layer of the neurolemmocyte (Schwann cell); also called sheath of Schwann

neurology - the branch of science that deals with the normal functioning and disorders of the nervous system

neuromuscular junction - an area of contact between the axon terminal of a motor neuron and the underlying sarcolemma of a muscle fiber (cell); also called a myoneural junction

neuron - a nerve cell, consisting of a cell body, dendrites and axon(s)

neuropeptide - molecule of two to about 40 amino acids that occurs naturally in the brain and acts primarily to modulate responses associated with neurotransmitters; examples are enkephalins and endorphins

neurophysin - small protein that aids in transport, storage, and subsequent release of oxytocin (OT) and antidiuretic hormone (ADH)

neurosecretory cell - cell in the paraventricular or supraoptic nucleus of the hypothalamus that produces oxytocin (OT) or antidiuretic hormone (ADH) that will be released subsequently from axonal endings in the neurohypophysis

neurosyphilis - form of the tertiary stage of syphilis in which various types of nervous tissue are attacked by bacteria and degenerate

neutrophil - a type of white blood cell characterized by granular cytoplasm and staining equally readily with acid or basic dyes

nicotinic receptor - a receptor found on both parasympathetic and sympathetic postganglionic neurons; so named because actions of acetylcholine (ACh) in such receptors are similar to those produced by nicotine application

nociceptor - a free (naked) nerve ending that detects pain

Node of Ranvier - a space, along a myelinated nerve fiber, between the adjacent neurolemmocytes (Schwann cells) that form the myelin sheath and the neurolemma; also called neurofibral node

nondisjunction - failure of sister chromatids or homologous chromosomes to separate properly during anaphase of mitosis (or equatorial division of meiosis) or reductional division of meiosis; both pass to the same daughter cell

norepinephrine (NE) - hormone secreted in small amounts by the adrenal medulla; produces actions similar to those resulting from stimulation of the sympathetic nervous system, where it is the transmitter substance for the postganglionic neurons; also called noradrenaline

notochord - flexible rod of embyronic tissue that lies where the future vertebral column will develop

nuclease - enzyme that breaks nucleotides into pentoses and nitrogenous bases; examples are ribonuclease and deoxyribonuclease

nucleic acid - organic compound that is a long polymer of nucleotides, each containing a pentose sugar, a phosphate group and one of five possible nitrogenous bases (adenine, cytosine, guanine, thymine, or uracil)

nucleolus - a nonmembranous spherical body within the nucleus; composed of protein, DNA, and RNA; it functions in the synthesis and storage of ribosomal RNA

nucleosome - the elementary structural subLETTER of a chromosome; it consists of histones and DNA

nucleus - spherical or oval organelle of a cell that contains the hereditary factors called genes; a cluster of unmyelinated nerve cell bodies in the CNS; the central portion of an atom, made up of protons and neutrons

nucleus cuneatus - a group of nerve cells in the inferior portion of the medulla in which fibers of the fasciculus cuneatus terminate

nucleus gracilis - a group of nerve cells in the inferior portion of the medulla in which fibers of the fasciculus gracilis terminate

nucleus pulposus - a soft, pulpy, highly elastic substance in the center of an intervertebral disc, a remnant of the notochord

nystagmus - rapid, involuntary, rhythmic movement of the eye-balls; horizontal, rotary, or vertical

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obesity - body weight 10-20 % over a desirable standard as a result of excessive fat accumulation; types include hypertrophic (adult-onset) and hyperplastic (lifelong)

obstetrics - the specialized branch of medicine that deals with pregnancy, labor, and the period of time immediately following delivery

obturator - anything that obstructs or closes a cavity or opening

occlusion - the act of closure or state of being closed

occult - concealed or hidden from view, as, for example, occult blood in stools

olfactory - pertaining to smell

oligodendrocyte - a neuroglial cell that supports neurons & produces a phospholipid myelin sheath around neuronal axons in the central nervous system

oligospermia - deficiency of spermatozoa in the semen

oliguria - a daily urinary output usually less than 250 ml

oncogene - a gene that has the ability to transform a normal cell into a cancerous cell

oncology - the study of tumors

oogenesis - formation and development of the ovum

oophorectomy - the surgical removal of the ovaries

open pneumothorax - refers to an opening in the chest wall large enough to disrupt the negative intrathoracic pressure required for spontaneous ventilation. Initial treatment may include positive pressure ventilation and/or rapid covering of the open wound with evacuation of the pleural space via tube thoracostomy.  For chest trauma cases, large-bore (> 32F) tubes are recommended for better evacuation of blood and other fluids. For related reasons, tubes are usually positioned posteriorly, in a dependent position for the supine patient.

ophthalmic - pertaining to the eye

ophthalmologist - physician who specializes in the diagnosis and treatment of eye disorders with drugs, surgery, and corrective lenses

ophthalmology - the study of the structure, function, and diseases of the eye

ophthalmoscopy - examination of the interior fundus of the eyeball to detect retinal changes associated with hypertension, diabetes mellitus, atherosclerosis, and increased intracranial pressure

opsin - the glycoprotein portion of a photopigment

opsonization - action of some antibodies that renders bacteria and other foreign cells more susceptible to phagocytosis; also called immune adherence

optic chiasma - crossing point of the optic (II) nerves, anterior to the pituitary gland

optician - a technician who fits, adjusts, & dispenses corrective lenses on prescription of an optometrist or an ophthalmologist

optometrist - specialist with a doctorate degree in optometry who is licensed to examine & test the eyes and to treat visual defects by prescribing corrective lenses

ora serrata - the irregular margin of the retina, lying internal and slightly posterior to the junction of the choroid and ciliary body

oral cholecystogram - X-ray examination of the gallbladder to evaluate for the presence of gallstones, inflammation, and tumors

orbit - the bony, pyramid-shaped cavity of the skull housing the eyeball

organelle - structure inside a cell having characteristic morphology, specialized to perform a specific function in cellular activities

organic compound - compound that always contains carbon and hydrogen and has the atoms held together by covalent bonds; examples include carbohydrates, lipids, proteins, and nucleic acids (DNA and RNA)

organism - a total living form; one individual

orgasm - sensory and motor events involved in ejaculation for the male and in involuntary contraction of the perineal muscles for the female at the climax of sexual intercourse

orifice - any aperture or opening

origin - the place of attachment of a muscle to the more stationary bone at a joint, or the end opposite the insertion

oropharynx - the second portion of the pharynx, lying posterior to the mouth and extending from the soft palate down to the hyoid bone

orthopedics - a branch of medicine dealing with preservation and restoration of the skeletal system, articulations, and related structures

orthopnea - dyspnea (discomfort in breathing) occuring when in the horizontal position

osmoreceptor - hypothalamic receptor that is sensitive to changes in blood osmotic pressure and that, in response to high osmotic pressure (low water concentration), causes the synthesis and release of antidiuretic hormone

osmosis - the net movement of water molecules through a selectively permeable membrane from an area of high water concentration to an area of lower water concentration until an equilibrium condition is achieved

osseus - bony

ossicle - a small bone, as those in the middle ear (incus, malleus, stapes)

ossification - the formation of bone; also called osteogenesis

osteoblast - cell formed from an osteo-progenitor cell; it participates in bone formation by secreting some organic components and inorganic salts

osteoclast - a large multinuclear cell that develops from a monocyte & destroys or resorbs bone tissue

osteocyte - a mature bone cell that maintains the daily activities of bone tissue

osteogenic layer - the inner layer of the periosteum, containing cells responsible for forming new bone during growth and repair

osteology - the study of bones

osteomalacia - deficiency of vitamin D in adults causing demineralization and softening of the bones

osteomyelitis - inflammation of bone marrow or of both the bone and marrow

osteoporosis - age-related disorder characterized by decreased bone mass and increased susceptibility to fractures; may result from decreased levels of estrogens

osteoprogenitor cell - a stem cell derived from mesenchyme, having mitotic potential and ability to differentiate into an osteoblast

otalgia - pain in the ear; earache

otic - pertaining to the ear

otitis media - acute infection of the middle ear, characterized by pain, malaise, fever, and an inflamed tympanic membrane that is subject to rupture

otolith - a particle of calcium carbonate embedded in the otolithic membrane; it functions in maintaining static equilibrium

otolithic membrane - a thick, gelatinous, glycoprotein layer, located directly over the hair cells of the macula in the saccule and utricle of the inner ear

otorhinolaryngology - the branch of medicine that deals with diagnosis and treatment of diseases of the ears, nose, and throat

ovarian follicle - a general name for oocytes (immature ova), regardless of their stage of development, along with their surrounding epithelial cells

ovary - female gonad; it produces ova and hormones (estrogens, progesterone, and relaxin)

ovulation - the rupture of a vesicular ovarian (Graafian) follicle, with discharge of a secondary oocyte into the pelvic cavity

ovum - the female reproductive or germ cell; an egg cell

oxidation - the removal of electrons and hydrogen ions from (or, less commonly, the addition of oxygen to) a molecule; it results in decreasing the molecule's energy content; glucose oxidation in the body is also called cellular respiration

oxyhemoglobin (HbO2) - hemoglobin combined with oxygen

oxytocin (OT) - hormone secreted by neurosecretory cells in the paraventricular (mainly) & supraoptic nuclei of the hypothalamus; stimulates contraction of both smooth muscle fibers in the uterus & contractile cells around mammary ducts

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Pacinian corpuscle - oval pressure receptor located in subcutaneous tissue and consisting of concentric layers of connective tissue wrapped around an afferent nerve fiber; also called a lamellated corpuscle

Paget's disease - disorder characterized by a greatly accelerated remodeling process; osteoclastic resorption is massive and new bone formation by osteoblasts is extensive, resulting in irregular thickening and softening of the bones

palate - the horizontal structure separating the oral and the nasal cavities; the roof of the mouth

palliative - serving to relieve or alleviate without curing

palpate - to examine by touch; to feel

palpitation - a fluttering of the heart or an abnormal rate or rhythm of the heart

pancreas - a soft, oblong organ lying along the greater curvature of the stomach and connected by a duct to the duodenum; it has both exocrine (pancreatic juice) and endocrine (insulin, glucagon, and somatostatin) secretions

pancreatic duct - a single large tube, LETTERing with the common bile duct from the liver and the gallbladder and draining pancreatic juice into the duodenum at the hepatopancreatic ampulla (ampulla of Vater); also called the duct of Wirsung

Papanicolaou test - a cytological staining test for detection and diagnosis of premalignant/malignant conditions of the female genital tract; epithelial cells scraped from the tract are smeared, fixed, stained, and examined microscopically; also called a Pap smear

papilla - a small nipple-shaped projection or elevation

paracrine - local hormone, such as histamine, that acts on neighboring cells

paralysis - loss or impairment of motor function due to a lesion of nervous or muscular origin

paranasal sinus - a mucus-lined air cavity in a skull bone; communicates with the nasal cavity; the paranasal sinuses are located in the frontal, maxillary, ethmoid, and spenoid bones

paraplegia - paralysis of both lower extremities

parasympathetic division - one subdivision of the autonomic nervous system; preganglionic cell bodies are in brain stem nuclei & lateral gray matter of the sacral spinal cord; it is concerned with activities conserving/restoring body energy; also called the craniosacral division

parathyroid gland - one of four small endocrine glands, embedded on the posterior surfaces of the lateral lobes of the thyroid gland

paraurethral gland - mucous gland embedded in the wall of the urethra; its duct opens on either side of the urethral orifice; also called Skene's gland

parenchyma - the functional parts of any organ, as opposed to tissue that forms its stroma or framework

parenteral - situated or occurring outside the intestines; referring to introduction of substances into the body other than by way of the intestines, such as intradermal, subcutaneous, intramuscular, intravenous, or intraspinal

parietal pleura - the outer layer of serous pleural membrane; encloses & protects the lungs; the layer that is attached to the wall of the pleural cavity

parotid gland - one of the paired salivary glands located inferior and anterior to the ears; connected to the oral cavity via a duct (Stensen's) that opens on the inside of the cheek opposite the upper second molar tooth

paroxysm - a sudden periodic attack or recurrence of symptoms of a disease

parturition - the act of giving birth to young; childbirth; delivery

patellar reflex - the extension of the leg by contraction of the quadriceps femoris muscle in response to tapping on the patellar ligament; also called the knee jerk

pathogen - any disease-producing organism

pathogenesis - the development of disease or a morbid or pathological state

pathological - pertaining to or caused by disease

pectinate muscles - projecting muscle bundles of the anterior atrial walls and lining of the auricles

pectoral - pertaining to the chest or breast

pediatrician - a physician specializing in the care and treatment of children and their illnesses

pedicel - a footlike structure, as on podocytes of a glomerulus

pelvic cavity - inferior portion of the abdominopelvic cavity, containing the urinary bladder, sigmoid colon, rectum, and internal female and male reproductive structures

pelvic splanchnic nerves - preganglionic parasympathetic fibers from the levels of S2, S3, and S4 that supply the urinary bladder, reproductive organs, and the descending and sigmoid colon and rectum

pelvimetry - measurement of the size of the inlet and outlet of the birth canal

penis - the male copulatory organ, used to introduce spermatozoa into the vagina of the female

percussion - act of striking (percussing) an underlying part of the body using short, sharp blows; aids in diagnosing the part by the quality of the sound produced

pericardial cavity - small potential space between the visceral and parietal layers of the serous pericardium; contains pericardial fluid

pericardium - a loose-fitting membrane that encloses the heart; it consists of an outer fibrous layer and an inner serous layer

perichrondrium - the membrane that covers cartilage

perikaryon - the nerve cell body; it contains the nucleus and other organelles

perilymph - fluid contained between the bony and membranous labyrinths of the inner ear

perimetrium - the serosa of the uterus

perimysium - an invagination of the epimysium, dividing muscles into bundles

perineum - the pelvic floor; the space between the anus and the scrotum in the male and between the anus and the vulva in the female

perineurium - connective tissue wrapping around fascicles in a nerve

periodontal disease - a collective term for conditions characterized by degeneration of gingivae, alveolar bone, periodontal ligament, and cementum

periosteum - membrane that covers bone and consists of connective tissue, osteoprogenitor cells, and osteoblasts; it is essential for bone growth, repair, and nutrition

peripheral - located on the outer part or a surface of the body

periphery - outer part or a surface of the body; part away from the center

peristalsis - successive muscular contractions along the wall of a hollow, muscular structure

peritoneum - largest serous membrane of the body; it lines the abdominal cavity and covers the viscera

peritonitis - inflammation of the peritoneum

permissive effect - an hormonal interaction in which target cell response to one hormone is enhanced by prior or simultaneous exposure to (an)other hormone(s); endometrial maturation by progesterone, following an exposure to estrogen, is an example

pernicious - fatal

peroxisome - organelle similar in structure to a lysosome; it contains enzymes involved in hydrogen peroxide metabolism; it is abundant in liver cells

Peyer's patches - aggregated lymph nodules that are most abundant in the ileum; also called aggregated lymphatic follicles

phagocytosis - the process by which cells (phagocytes) ingest particulate matter; especially ingestion and destruction of microbes, cell debris, and other foreign matter

phalanx - the bone of a finger or toe; plural, phalanges

pharmacology - science that deals with the effects and uses of drugs in the treatment of disease

pharynx - the throat; tube that starts at the internal nares and runs partway down the neck, where it opens into the esophagus posteriorly and the larynx anteriorly

phenotype - the observable expression of genotype; physical characteristics of an organism, determined by the genetic makeup and influenced by interactions between genes and internal and external environmental factors

phenylketonuria (PKU) - a disorder characterized by elevated levels of the amino acid phenylalanine in the blood

pheochromocytoma - a tumor of the chromaffin cells of the adrenal medulla; results in hypersecretion of medullary hormones

phlebitis - inflammation of a vein, usually in the lower extremities

phlebotomy - cutting of a vein to allow the escape of blood

phosphocreatine - a high-energy molecule in skeletal muscle fibers (cells); phosphocreatine breaks down into creatine, phosphate, and energy; the energy is used to generate ATP from ADP

phospholipid bilayer - the arrangement of phospholipid molecules in two parallel rows, in which the hydrophilic heads face outward & the hydrophobic tails face inward

phosphorylation - the addition of a phosphate group to a chemical compound; the types include substrate-level, oxidative, and photophosphorylation

physiology - science that deals with the functions of an organism or its parts

pia mater - inner membrane (meninx), covering the brain and the spinal cord

piezoelectric effect - a response of bone, mainly collagen, to stress; very minute currents of electricity are produced and they are believed to stimulate osteoblasts to make new bone cells

pilonidal - denoting a growth of hairs, resembling a tuft, inside a cyst or a sinus

pineal gland - a cone-shaped gland located in the roof of the third ventricle; also called the epiphysis cerebri

pinealocyte - secretory cell of the pineal gland; produces hormones

pinna - the projecting part of the external ear, composed of elastic cartilage and covered by skin; shaped like the flared end of a trumpet; also called the auricle

pinocytosis - the process by which cells ingest liquid

pituicyte - supporting cell of the posterior lobe of the pituitary gland

pituitary dwarfism - condition caused by hyposecretion of human growth hormone (hGH) during the growth years and characterized by childlike physical traits in an adult

placenta - special structure through which exchange of materials between fetal and maternal circulations occurs; also called the afterbirth

plantar flexion - bending the foot in the direction of the plantar surface (sole)

plaque - any cholesterol-containing mass in the tunica media of arteries; a mass of bacterial cells, dextran (polysaccharide), and other debris that adheres to teeth

plasma - extracellular fluid found in blood vessels; blood minus the formed elements

plasmapheresis - procedure in which blood is withdrawn from the body, its components are selectively separated, undesireable components (e.g., toxins, metabolic substances, and antibodies) causing disease are removed, and the remainder is returned to the body

pleura - the serous membrane that covers the lungs and lines the walls of the chest and diaphragm

plexus - a network of nerves, veins, or lymphatic vessels

pluripotent hematopoietic stem cell - immature stem cell in bone marrow that gives rise to precursors of all the different mature blood cells; also called a hemocytoblast

pneumonia - acute infection or inflammation of the alveoli of the lungs

pneumotaxic area - portion of the respiratory center in the pons; it sends inhibitory nerve impulses continually to the inspiratory area to limit inspiration and to facilitate expiration

podiatry - diagnosis and treatment of foot disorders

poliomyelitis - a viral infection marked by fever, headache, stiff neck and back, deep muscle pain and weakness, and loss of certain somatic reflexes; a serious form, bulbar polio, results in destruction of motor neurons in anterior horns of the spinal nerves, leading to paralysis

polycythemia - disorder characterized by hematocrit above normal level of 55; hypertension, thrombosis, & hemorrhage occur

polyp - a tumor on a stem, especially on a mucous membrane

polysaccharides - carbohydrates in which 3 or more monosaccharides are joined chemically

polyuria - an excessive production of urine

pons - portion of the brain stem that forms a bridge between the medulla and the midbrain, anterior to the cerebellum

posterior - nearer to or at the back of the body; also called dorsal

postganglionic neuron - the second visceral motor neuron in an autonomic pathway, having its cell body and dendrites located in an autonomic ganglion and its unmyelinated axon ending at cardiac muscle, smooth muscle, or a gland

postpartum - after parturition; occurring after the delivery of a baby

postsynaptic neuron - the nerve cell that is activated by release of a neurotransmitter substance from another neuron and carries nerve impulses away from the synapse

preeclampsia - syndrome during pregnancy characterized by sudden hypertension, excessive amounts of protein in the urine, and generalized edema; it might be related to an autoimmune or allergic reaction because of the presence of a fetus

preganglionic neuron - the first visceral efferent neuron in an autonomic pathway; its cell body and dendrites are in the brain or spinal cord and its myelinated axon synapses with a postganglionic neuron in an autonomic ganglion

premonitory - giving previous warning, as premonitory symptoms

prepuce - loose-fitting skin covering the glans of the penis or clitoris; also called the foreskin

presbyopia - a loss of elasticity of the lens of the eye due to advancing age, with resulting inability to focus clearly on near objects

presynaptic inhibition - inhibition of a nerve impulse before it reaches a synapse; neurotransmitter released by the inhibitory neuron depresses release of excitatory transmitter at the excitatory neuron

prevertebral ganglion - a cluster of cell bodies of postganglionic sympathetic neurons, anterior to the spinal column and close to large abdominal arteries; also called a collateral ganglion

primigravida - a woman pregnant for the first time

primordial - existing first; especially the primordial egg cells in the ovary

proctology - the branch of medicine that treats the rectum and its disorders

progeny - offspring or descendants

progesterone (PROG) - a female sex hormone produced by the ovaries; it matures cells of the uterine endometrium and the mammary glands during the luteal phase of a menstrual cycle

prognosis - a forecast of the probable results of a disorder; the outlook for recovery

projection - the process by which the brain refers sensations to their point of stimulation

prolactin (PRL) - a hormone secreted by the adenohypophysis (anterior lobe) of the pituitary gland; initiates and maintains milk secretion by the mammary glands

prolapse - a dropping or falling down of an organ, especially the uterus or the rectum

proliferation - the rapid and repeated production of new parts, especially cells

pronation - a movement of the forearm in which the palm of the hand is turned posteriorly or inferiorly

properdin - a protein found in serum capable of destroying bacteria and viruses

prophase - the first stage of mitosis during which the chromatid pairs form and aggregate around the equatorial region of the cell

proprioception - the receipt of information from muscles, tendons, and the labyrinth, enabling the brain to determine movements and to position the body and its parts; also called kinesthesia

proprioceptor - a receptor located in muscles, tendons, or joints; it provides information about body position and movements

prostaglandin (PG) - membrane-associated lipid composed of 20-carbon fatty acids, with 5 carbon atoms joined to form a cyclopentane ring; it is synthesized in small quantities and, basically, mimics the activities of hormones

prostate gland - the doughnut-shaped gland inferior to the male urinary bladder; it surrounds the upper part of the urethra and it secretes a slightly acid solution that contributes to sperm motility and viability

prostatectomy - surgical removal of part of the prostate gland or surgical removal of the entire prostate gland

prosthesis - artificial device to replace a missing body part

prothrombin - an inactive protein synthesized by the liver, released into the blood, and converted to active thrombin in the process of blood clotting

proto-oncogene - gene responsible for some aspect of normal growth and development; it may be transformed into an oncogene, a gene capable of causing cancer

protraction - movement of the mandible or shoulder girdle forward on a plane parallel with the ground

proximal - nearer the attachment of an extremity to the trunk or a structure; nearer to the point of origin

pruritis - itching

pseudopods - temporary, protruding projections of cytoplasm

psoriasis - chronic disease of the skin, characterized by reddish plaques or papules covered with scales

psychosomatic - pertaining to the relation between mind and body; commonly used to refer to those physiological disorders thought to be caused, entirely or partly, by emotional disturbances

pterygopalatine ganglion - a cluster of cell bodies of parasympathetic post-ganglionic neurons, ending at the lacrimal and nasal glands

ptosis - drooping, as of the eyelid or the kidney

puberty - time of life during which the secondary sex characteristics begin to appear and capability for sexual reproduction is developed; usually between the ages of 10 and 17

puerperium - state immediately after childbirth, usually 4-6 weeks

pulmonary - concerning or affected by the lungs

pulmonary contusion - Pulmonary contusion usually results from a severe blow to the chest that typically causes one or more fractures. As mentioned previously, most pulmonary contusions are related to the finding of a flail chest. Even if not readily apparent enough to be life-threatening on initial evaluation, the resultant hemorrhage, edema, and inflammation of the affected lung may later result in decreased oxygenation and impaired ventilation. Treatment is usually individualized based on the respiratory needs of the patient. If pulmonary contusion is noted during the initial resuscitation, mechanical ventilation will usually be necessary. During the subsequent evaluation, therapy directed at the pulmonary contusion may prevent initiation of mechanical ventilation with its attendant risks.  Therapy includes limitation of crystalloid fluid administration, aggressive pulmonary toilet, and regional pain control.

punctate distribution - unequal distribution of cutaneous receptors

pyelitis - inflammation of the kidney pelvis and its calyces

pyemia - infection of the blood, with multiple abscesses, caused by pus-forming organisms

pyloric sphincter - a thickened ring of smooth muscle through which the pylorus of the stomach communicates with the duodenum; also called the pyloric valve

pyogenesis - the formation of pus

pyorrhea - a discharge of flow of pus, especially in the alveoli (sockets) and the tissues of the gums

pyramid - a pointed or cone-shaped structure; in the CNS, 1 of 2 triangular structures on the ventral medulla, comprising the largest motor tracts from cerebral cortex to spinal cord; triangular renal medullary structure comprising straight segments of renal tubules

pyramidal pathways - collections of motor nerve fibers arising in the brain and passing down through the spinal cord to motor cells in the anterior horns

pyrexia - a condition in which temperature is above normal

pyuria - presence of leucocytes and other components of pus in urine
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quadrant - one of four parts

quadriplegia - paralysis of the two upper and two lower extremities
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- R -

radiographic anatomy - diagnostic branch of anatomy that includes the use of X-rays

rales - sounds sometimes heard in lungs; resemble bubbling or rattling; due to presence of an abnormal amount or type of fluid or mucus inside bronchi or alveoli or to bronchoconstriction, so that air cannot enter or leave the lungs normally

rami communicantes - branches of a spinal nerve; singular, ramus communicans

Raynaud's disease - vascular disease, primarily of females, characterized by bilateral attacks of ischemia, usually of the fingers and toes; the skin becomes pale and exhibits burning and pain as a result of exposure to cold or to emotional stimuli

reactivity - the ability of an antigen to react specifically with the antibody whose formation it induced

reciprocal innervation - the phenomenon by which action potentials stimulate contraction of one muscle and simultaneously inhibit contraction of antagonistic muscles

recruitment - the process of increasing the number of active motor LETTERs; also called motor LETTER summation

rectum - the last 20 cm (7 in.) of the gastrointestinal tract, from the sigmoid colon to the anus

recumbent - lying down

refraction - the bending of light as it passes from one medium to another

refractory period - the time during which an excitable cell cannot be made to respond to a stimulus that is usually adequate to evoke an action potential

regeneration - the natural renewal of a structure

regimen - strictly regulated scheme of diet, exercise, or activity designed to achieve certain ends

regurgitation - a return of solids or fluids from the stomach to the mouth; blood flow backward through incompletely closed heart valves

relapse - return of a disease, weeks or months after its apparent cessation

renal corpuscle - the glomerular (Bowman's) capsule and its enclosed glomerulus

renal erythropoietic factor - an enzyme released by the kidneys and liver in conditions of hypoxia; acts on a plasma protein to bring about production of eyrthropoietin, a hormone that stimulates red blood cell production

renin - an enzyme released by the kidney into plasma, where it converts angiotensinogen into angiotensin I

renin-angiotensin pathway - mechanism for the control of aldosterone secretion by angiotensin II; initiated by secretion of renin from the kidney, in response to low blood pressure

reproduction - the formation of new cells for growth, replacement, or repair, or the production of a new individual

residual volume - the volume of air still contained in the lungs after maximal expiration; about 1,200 ml

resistance - resistance to blood flow as a result of viscosity, blood vessel length, and blood vessel radius; hindrance to the flow of electricity; hindrance to the flow of air as it moves through the respiratory pasageways; the abililty to ward off disease

respiration - overall exchange of gases among the atmosphere, the blood, and the body cells; it consists of pulmonary ventilation, external respiration, & internal respiration

respirator - apparatus fitted to a mask over the nose and mouth, or hooked directly to an endotracheal or tracheostomy tube; it is used to assist or support ventilation or to provide nebulized medication to the air passages under positive pressure

resuscitation - the act of bringing a person back to full consciousness

rete testis - the network of ducts in the testis

retention - a failure to void urine due to obstruction, nervous contraction of the urethra, or absence of sensation of the desire to urinate

reticular activating syst. - the extensive network of branched nerve cells running through the core of the brain stem; when these cells are activated, a generalized alert or arousal behavior results

reticulocyte - an immature red blood cell

reticulum - a network

retina - inner coat of the eyeball, lying only in the posterior portion of the eye and consisting of nervous tissue and a pigmented layer comprising epithelial cells lying in contact with the choroid; also called the nervous tunic

retinal - the pigment portion of the photopigment rhodopsin; also called visual yellow

retraction - movement of a protracted part of the body backward on a plane parallel to the ground, as in pulling the lower jaw back into line with the upper jaw

retroflexion - positioning of the uterus in which it is tilted posteriorly

retrograde degeneration - the changes occuring in the proximal portion of a damaged axon only as far as the first neurofibral node (of Ranvier); similar to the changes that occur during Wallerian degeneration

retroperitoneal - external to the peritoneum lining the abdominal cavity

rheumatism - a painful state of the supporting structures of the body, bones, ligaments, joints, tendons, or muscles

rhinology - the study of the nose and its disorders

rhinoplasty - the surgical procedure in which the structure of the external nose is altered

rhodopsin - the photopigment in rods of the retina, consisting of a protein scotopsin plus retinal; it is sensitive to low levels of illumination; also called visual purple

ribonucleic acid (RNA) - a single-stranded nucleic acid; nucleotides consist of a base (adenine, cytosine, guanine, or uracil), ribose, and phosphate; the three types are messenger (m-RNA), transfer (tRNA), and ribosomal (rRNA), all of which are necessary for protein synthesis

ribosome - organelle in the cytoplasm of cells; composed of ribosomal RNA and ribosomal proteins; nicknamed the protein factory because of its role in protein synthesis

rickets - condition affecting children deficient in vitamin D; characterized by soft and deformed bones, resulting from abnormal calcium metabolism

rigidity - hypertonia characterized by increased muscle tone; reflexes are not affected

roentgen - internation LETTER of radiation; a standard quantity of X or gamma radiation

roentgenogram - image produced by X-rays on a photographic film

rotation - movement of a bone around its own axis, with no other movement

rugae - large folds in the mucosa of an empty hollow organ, such as the stomach or the vagina
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- S -

saccule - the lower and smaller of two chambers in the membranous labyrinth inside the vestibule of the inner ear; it contains a receptor organ for static equilibrium

sacral promontory - the superior surface of the body of the first sacral vertebra that projects anteriorly into the pelvic cavity; a line from the sacral promontory to the superior border of the pubic symphysis divides the abdominal and pelvic cavities

sagittal plane - vertical plane that divides the body or organs into left and right portions; such a plane may be midsagittal (median), with equal divisions, or parasagittal, with unequal divisions

saliva - a clear, alkaline, somewhat viscous secretion produced by the three pairs of salivary glands; contains various salts, mucin, lysozyme, and salivary amylase

salivary amylase - enzyme in saliva that initiates the chemical breakdown of starch, mostly in the mouth

salpingitis - inflammation of the uterine (Fallopian) or auditory (Eustachian) tube

sarcolemma - cell membrane of a muscle fiber (cell), especially, of a skeletal muscle fiber

sarcoma - a connective tissue tumor, often highly malignant

sarcomere - the contractile LETTER in a striated muscle fiber (cell) extending from one Z line to the next Z line

sarcoplasm - the cytoplasm of a muscle fiber (cell)

sarcoplasmic reticulum - a network of saccules and tubes surrounding the myofibrils of a muscle fiber (cell), comparable to endoplasmic reticulum; functions to reabsorb calcium ions during relaxation and to release them to cause contraction

satiety - fullness or gratification, as of hunger or thirst

scala tympani - lower spiral-shaped channel of the bony cochlea, filled with perilymph

scala vestibuli - upper spiral-shaped channel of the bony cochlea, filled with perilymph

sciatica - inflammation & pain along the sciatic nerve; felt at the back of the thigh, running down the inside of the leg

sclera - the white coat of fibrous tissue forming the outer protective covering over the eyeball, except in the most anterior portion; the posterior portion of the fibrous tunic

sclerosis - a hardening of tissues with loss of elasticity

scoliosis - abnormal lateral curvature compared with the normal vertical line of the backbone

scotoma - area of depressed or lost vision within the visual field

scotopsin - the protein portion of the visual pigment rhodopsin, found in rods of the retina

scrotum - a skin-covered pouch that contains the testes and their accessory structures

sebaceous - secreting oil

sebum - the secretion of sebaceous (oil) glands

secretion - production and release from a gland cell of a fluid, especially a functionally useful fluid as opposed to a waste product

sella turcica - depression on the superior surface of the sphenoid bone; houses the pituitary gland

semen - a fluid discharged at ejaculation by a male; consists of a mixture of spermatozoa and the secretions of the seminal vesicles, the prostate gland, and the bulbourethral (Cowper's) glands; also called seminal fluid

semilunar valve - valve guarding the entrance into the aorta or pulmonary trunk from a ventricle of the heart

seminal vesicle - one of a pair of convoluted pouchlike structures, lying posterior and inferior to the urinary bladder and anterior to the rectum in the male; they secrete a component of semen into the ejaculatory ducts

seminiferous tubule - tightly coiled duct, located in a lobule of the testis, in which spermatozoa are produced

senescence - the process of growing old; the period of old age

senile macular degeneration - a disease in which blood vessels grow over the macula lutea

senility - loss of mental or physical ability due to old age

sepsis - a morbid condition that results from the presence, in blood or body tissues, of pathogenic bacteria & their products

septicemia - presence of toxins or disease-causing bacteria in blood; also called blood poisoning

serosa - any serous membrane; the outermost layer of any organ, formed by a serous membrane; the membrane that lines pleural, pericardial, & peritoneal cavities

serous membrane - a membrane that lines a body cavity that does not open to the exterior; also called the serosa

sesamoid bones - small bones usually found in tendons

sigmoid colon - the S-shaped portion of the large intestine, beginning at the level of the left iliac crest, projecting inward toward the midline, and terminating at the rectum, at about the level of the third sacral vertebra

sigmoidoscopy - visualization of the anal canal, rectum, and colon to: screen for colorectal cancer, collect samples for biopsy, remove polyps, gather specimens for culture, and photograph the intestinal mucosa

simple pneumothorax - Usually diagnosed with a chest radiograph, pneumothorax represents injury to the visceral pleura of the lung resulting in air accumulation within the pleura space. This is differentiated from a tension pneumothorax as the air space is not under pressure and generally has no hemodynamic significance. Treatment consists of tube thoracostomy.

sinoatrial (SA) node - a compact mass of cardiac muscle fibers (cells) that are specialized for conduction & located in the right atrium beneath the opening of the superior vena cava; also called the sinuatrial node or pacemaker

sinus - hollow in a bone (paranasal sinus) or other tissue; a channel for blood (vascular sinus); any cavity having a narrow opening

sinusitis - an inflammation of the mucous membrane of a paranasal sinus

sinusoid - microscopic space or passage for blood in certain organs, such as the liver or spleen

Snellen test - a test used to evaluate any problems or changes in vision by measuring visual acuity

somatic nervous system - a portion of the peripheral nervous system made up of the somatic efferent fibers that run between the central nervous system and the skeletal muscles and skin

somatomedin - a small protein produced by the liver in response to human growth hormone (hGH) stimulation; it mediates most of the effects of hGH

somesthetic - pertaining to sensations & sensory structures of the body

somite - block of mesodermal cells in a developing embryo; can be distinguished into a myotome (forms most of the skeletal muscles), a dermatome (forms connective tissues), and a sclerotome (forms the vertebrae)

spasm - a sudden, involuntary contraction of large groups of muscles

spastic - being characterized by an increase in muscle tone (stiffness), accompanying increased tendon reflexes and abnormal reflexes (Babinski sign)

spasticity - hypertonia, characterized by increased muscle tone, increased tendon reflexes, and pathological reflexes (Babinski sign)

spermatic cord - supporting structure of the male reproductive system, extending from the testis to the deep inguinal ring; it includes the ductus (vas) deferens, arteries, veins, lymphatics, nerves, a cremaster muscle, and connective tissue

spermatogenesis - formation and development of spermatozoa in the seminiferous tubules of the testis

spermatozoon - a mature sperm cell

spermicide - any agent that kills spermatozoa

spermiogenesis - the maturation of spermatids into spermatozoa

sphincter - circular muscle constricting an orifice

sphygmomanometer - instrument for measuring arterial blood pressure

spina bifida - a congenital defect of the vertebral column in which the halves of the neural arch of a vertebra fail to fuse in the midline

spinal cord - a mass of nerve tissue located in the vertebral canal from which 31 pairs of spinal nerves originate

spinous process - sharp or thornlike process or projection; also called a spine; the sharp ridge running diagonally across the posterior surface of the scapula

spirometer - apparatus used to measure air capacity of the lungs

splanchnic - pertaining to the viscera

spleen - a large mass of lymphatic tissue between the fundus of the stomach and the diaphragm; functions in phagocytosis, the production of lymphocytes, and blood storage

sputum - substance ejected from the mouth, containing saliva and mucus

squamous - scalelike

starvation - loss of energy stores in the form of glycogen, fats, and proteins, due to inadequate intake of nutrients or inability to digest, absorb, or metabolize ingested nutrients

stasis - a stagnation or halt of normal flow of fluids (as the blood or urine) or of the intestinal mechanism

static equilibrium - the maintenance of posture in response to changes in the orientation of the body, mainly the head, relative to the ground

stell. reticuloendothel. cell - phagocytic cell that lines a sinusoid of the liver; also called a Kupffer's cell

stenosis - an abnormal narrowing or constriction of a duct or opening

stereocilia - groups of extremely long, nonmotile microvilli, projecting from the epithelial cells lining the epididymis

stereognosis - an ability to recognize the size, shape, and texture of an object by touch

sterile - free from any living micro-organisms; unable to conceive or produce offspring

sterilization - an elimination of all living microorganisms; rendering an individual incapable of reproduction; e.g., castration, vasectomy, or hysterectomy

strabismus - a condition in which the visual axes of the two eyes differ, so that they do not fix on the same object; condition of being cross-eyed

stratum basalis - the outer layer of endometrium, next to the myometrium, that is maintained during menstruation and gestation; it produces a new functionalis following menstruation or parturition

stratum functionalis - the inner layer of the endometrium, adjacent to the uterine cavity, that is shed during menstruation; forms the maternal portion of the placenta during gestation

stricture - a local constriction of a tubular structure

stroma - the tissue that forms the ground substance, foundation, or framework of an organ, as opposed to its functional parts

stupor - state of unresponsiveness from which a patient can be aroused only briefly and by vigorous and repeated stimulation

subarachnoid space - space between the arachnoid and the pia mater; it surrounds the brain and the spinal cord; cerebrospinal fluid circulates through it

subcutaneous - underneath the skin; also called hypodermic

subdural space - a space between the dura mater and the arachnoid of the brain and spinal cord; it contains a small amount of fluid

sublingual gland - one of the pair of salivary glands situated in the floor of the mouth under the mucous membrane, to the side of the lingual frenulum; its duct (Rivinus's) opens into the floor of the mouth

submandibular gland - salivary gland beneath the base of the tongue under the mucous membrane in the posterior floor of the mouth (behind sublingual glands); duct (Wharton's) situated to the side of the lingual frenulum; also called the submaxillary gland

submucosa - layer of connective tissue located beneath a mucous membrane, as in the gastrointestinal tract or the urinary bladder; the submucosa connects the mucosa to the muscularis tunic

subserous fascia - layer of connective tissue internal to the deep fascia, lying between deep fascia and the serous membrane lining the body cavities

sudoriferous gland - an apocrine or exocrine gland in the dermis or subcutaneous layer; produces perspiration; also called a sweat gland

sulcus - groove or depression between parts, especially between the convolutions of the brain; plural, sulci

summation - algebraic addition of the excitatory and inhibitory effects of all stimuli applied simultaneously to a nerve cell body (spatial); increased strength of muscle contraction resulting when stimuli occur in rapid succession (temporal)

superficial - located on or near the surface of the body

superior - toward the head of upper part of a structure; also called cephalad or craniad

supination - movement of the forearm in which the palm of the hand is turned anteriorly or superiorly

suppuration - pus formation & discharge

surfactant - a phospholipid substance produced by the lungs; it decreases surface tension

susceptibility - a lack of resistance of a body to the deleterious or other effects of agents such as pathogenic micro-organisms

suspensory ligament - fold of peritoneum extending laterally from the surface of the ovary to the pelvic wall

sustentacular cell - a supporting cell of seminiferous tubules; produces a hormone (inhibin) as well as secretions supplying nutrients to spermatozoa; also called a Sertoli cell

sutural bone - small bone located within a suture between certain cranial bones; also called Wormian bone

suture - an immovable fibrous joint in the skull where bone surfaces are closely LETTERed

sympathetic division - autonomic nervous system subdivision; preganglionic neuron cell bodies are in thoracic and upper lumbar segments of the spinal cord; primarily concerned with processes involving energy expenditure; also called the thoracolumbar division

sympathomimetic - producing effects mimicking those brought about by the sympathetic division of the autonomic nervous system

symphysis - a line of union; a slightly movable cartilaginous joint, e.g., the symphysis pubis between the anterior surfaces of the coxal (hip) bones

symptom - a subjective change in body function not apparent to an observer, such as fever or nausea, that indicates the presence of a disease or disorder of the body

synapse - the junction between the processes of two adjacent neurons; the place where the activity of one neuron affects the activity of another; may be electrical or chemical

synapsis - the pairing of homologous chromosomes during prophase I of meiosis

synaptic cleft - the narrow gap that separates the axon terminal of one nerve cell from another nerve cell or muscle fiber (cell) and across which a neurotransmitter diffuses to affect the postsynaptic cell

synarthrosis - an immovable joint

synchondrosis - a cartilaginous joint in which connecting material is hyaline cartilage

syncope - a faint; sudden temporary loss of conciousness associated with loss of postural tone and followed by a spontaneous recovery; most commonly caused by cerebral ischemia

syndesmosis - a fibrous joint in which articulating bones are LETTERed by dense fibrous tissue

syndrome - a group of signs and symptoms that occur together in a pattern that is characteristic of a particular disease or abnormal condition

syneresis - process of clot retraction

synergist - a muscle that assists the prime mover by reducing undesired action or unnecessary movement

synergistic effect - a hormonal interaction in which the effects of two or more hormones complement each other so that the target cell responds to the sum of the hormones; an example is the combined actions of estrogens, progesterone, prolactin, and oxytocin in lactation

synostosis - a joint in which the dense fibrous connective tissue that LETTERes bones at a suture has been replaced by bone, resulting in a complete fusion across the suture line

synovial cavity - the space between the articulating bones of a synovial (diarthrotic) joint filled with synovial fluid; also called a joint cavity

syphilis - a sexually transmitted disease caused by the bacterium Treponema pallidum

systemic lupus erythematosus - autoimmune inflammatory disease that may affect every tissue of the body; characterized by weakness, fever, fatigability, joint pain or arthritis, reddish skin lesions, lymphadenopathy, and malfunctions of many organ systems; also called SLE

systole - a part of the cardiac cycle; the phase of contraction of the heart muscle, especially the ventricles

systolic blood pressure - force exerted by blood on the arterial walls during ventricular contraction; highest pressure measured in the large arteries, about 120 mm Hg under normal conditions for young, adult males
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tachycardia - a rapid heartbeat or pulse rate

tactile - pertaining to the sense of touch

taenia coli - one of the three flat bands of thickened, longitudinal muscles running the length of the large intestine

tarsus - a collective term for the seven bones of the ankle

Tay-Sachs disease - inherited, progressive neuronal degeneration of the central nervous system due to a deficient lysosomal enzyme; it causes excessive accumulations of a lipid called ganglioside

tectorial membrane - gelatinous membrane projecting over, and in contact with, the hair cells of the spiral organ (organ of Corti) in the cochlear duct

telophase - final stage of mitosis, in which the daughter nuclei become established

tendon - a white fibrous cord of dense, regularly arranged connective tissue that attaches muscle to bone

tension pneumothorax - Injury to the visceral pleura of the lung or other portions of the upper airway may result in a rapid, one-way accumulation of air within the pleural space. Eventually, intrapleural pressure increases and causes compression of the mediastinal structures. The end result is depression of venous return to the heart, resulting in significant hemodynamic instability. Hallmarks include decreased breath sounds on the affected side, deviation of the trachea away from the affected side, and marked hypotension. Diagnosis is generally clinical, and not radiographic. Treatment consists of rapid evacuation of the air within the pleural space. This may be done initially with something as simple as a needle or intrevenous catheter. Tube thoracostomy then follows. This situation is exacerbated by the presence of positive pressure ventilation. More definitive treatment generally depends on the nature of the injury.

tenosynovitis - inflammation of a tendon sheath and synovial membrane at a joint

tentorium cerebelli - a transverse shelf of dura mater; forms a partition between the occipital lobe of the cerebral hemisphere and the cerebellum; covers the cerebellum

teratogen - agent or factor that causes physical defects in developing embryos

terminal ganglion - cluster of postganglionic parasympathetic neuronal cell bodies, either lying very close to the visceral effectors or located within the walls of the visceral effectors supplied by those postganglionic fibers

testis - a male gonad; it produces sperm and the hormones testosterone and inhibin; also called a testicle; plural, testes

testosterone - male sex hormone (androgen) secreted by interstitial endocrinocytes (cells of Leydig) of mature testes; controls growth and development of male sex organs

tetanus - infectious disease caused by the toxin of Clostridium tetani and characterized by tonic muscle spasms, exaggerated reflexes, lockjaw, and arching of the back; a smooth, sustained contraction produced by a series of very rapid stimuli to a muscle

tetany - a nervous condition caused by hypoparathyroidism & characterized by intermittent or continuous tonic muscle contractions of the extremities

tetralogy of Fallot - combination of congenital heart defects: 1) constricted pulmonary semilunar valve, 2) interventricular septal opening, 3) emergence of aorta from both ventricles (instead of from left only), and 4) enlarged right ventricle

thalamus - large, oval structure located above the midbrain and consisting of two masses of gray matter covered by a thin layer of white matter

thalassemia - group of hereditary hemolytic anemias

thallium imaging - diagnostic procedure used to evaluate: blood flow through coronary arteries, cardiac disorders, & effectiveness of drug therapy; thallium concentrates in healthy myocardial tissue

therapy - the treatment of a disease or disorder

thermoreceptor - any receptor that detects changes in temperature

thoracic cavity - superior component of the ventral body cavity; it contains two pleural cavities, the mediastinum, and the pericardial cavity

thoracolumbar outflow - fibers of the sympathetic preganglionic neurons; they have their cell bodies in the lateral gray columns of thoracic and upper lumbar segments of the spinal cord

thorax - the chest; the upper part of the trunk between the neck and the abdomen

thrombin - the active enzyme formed from prothrombin; acts to convert fibrinogen to fibrin

thrombocyte - a fragment of cytoplasm; is enclosed in a cell membrane and lacks a nucleus; found in the circulating blood; plays a role in blood clotting; also called a platelet

thrombolytic agent - chemical injected into the blood to dissolve clots and restore circulation through direct or indirect activation of plasminogen; examples include tissue plasminogen activator (t-PA), streptokinase, & urokinase

thrombophlebitis - a disorder in which inflammation of the wall of a vein is followed by blood clot (thrombus) formation

thrombosis - formation of a clot in an unbroken blood vessel, usually a vein

thymectomy - surgical removal of the thymus gland

thymus - a bilobed organ, located in the upper mediastinum posterior to the sternum and between the lungs that plays an essential role in the immune mechanism of the body

thyroglobulin (TGB) - a large glycoprotein molecule, secreted by follicle cells of the thyroid gland, in which iodine and tyrosine are combined to form thyroid hormones

thyroid cartilage - largest single cartilage of the larynx, consisting of two fused plates that form its anterior wall; also called the Adam's apple

thyroxine (T4) - a hormone secreted by the thyroid gland; it regulates growth and development, organic metabolism, and the activity of the nervous system

tinnitus - ringing, roaring, or clicking in the ears

tonometry - a test used to measure the intraocular pressure as a screen for glaucoma

tonsil - a multiple aggregation of large lymphatic nodules, embedded in mucous membrane

topical - applied to a surface, rather than ingested or injected

torpor - state of lethargy and sluggishness preceding stupor, which precedes semicoma, which precedes coma

toxic - pertaining to poison; poisonous

trabecula - an irregular latticework of thin plate of spongy bone; fibrous cord of connective tissue serving as supporting fiber by forming a septum that extends into an organ from its wall or capsule; plural, trabeculae

trabeculae carneae - ridges and folds in the myocardium of the ventricles

trachea - a tubular air passageway, extending from the larynx to the fifth thoracic vertebra; also called the windpipe

tracheostomy - creation of an opening into the trachea through the neck (below the cricoid cartilage), with insertion of a tube to facilitate passage of air or evacuation of secretions

trachoma - chronic infectious disease of the conjunctiva and cornea of the eye, caused by Chlamydia trachomatis

transfusion - a transfer of whole blood, blood components, or bone marrow, directly into the bloodstream

transient ischemic attack - an episode of temporary, focal, nonconvulsive cerebral dysfunction, caused by interference with the blood supply to the brain

transplantation - the replacement of injured or diseased tissues with natural ones from another part or another individual

transverse colon - portion of the large intestine extending across the abdomen from right colic (hepatic) flexure to left colic (splenic) flexure

trauma - an injury, either a physical wound or a psychic disorder, caused by an external agent or force, such as a physical blow or emotional shock; the agent or force that causes the injury

tremor - rhythmic, involuntary, purposeless contraction of opposing muscle groups

treppe - the gradual increase in the amount of contraction of a muscle caused by rapid, repeated stimuli of the same strength

triad - a complex of three LETTERs in a muscle fiber (cell), composed of a transverse tubule and the segments of sarcoplasmic reticulum on both sides of it

tricuspid valve - the atrioventricular (AV) valve on the right side of the heart

trigeminal neuralgia - pain in one or more of the branches of the trigeminal (V) nerve; also called tic doloureux

triglyceride - a lipid compound formed from one molecule of glycerol and three molecules of fatty acids; used for concentrated energy storage; prime component of adipose (fat) tissue; also called a neutral fat

trigone - triangular area at the base of the urinary bladder

triiodothyronine (T3) - a hormone produced by the thyroid gland; it regulates growth and development, organic metabolism, and the activity of the nervous system

trochlea - a pulley-like surface

trophoblast - the outer covering of cells of the blastocyst

tropic hormone - a hormone whose target is another endocrine gland

tubal ligation - a sterilization procedure in which the uterine (Fallopian) tubes are tied and cut

tuberculosis - infection of the lungs and pleurae caused by Mycobacterium tuberculosis

tumor - a growth of excess tissue due to an unusually rapid division of cells

tunica albuginea - the dense layer of white fibrous tissue covering a testis or deep to the surface of an ovary

tympanic antrum - air space in the posterior wall of the middle ear; it leads into the mastoid air cells or sinus
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ulcer - an open lesion of the skin or a mucous membrane of the body with loss of substance and necrosis of the tissue

umbilical - pertaining to the umbilicus or navel

umbilicus - small scar on the abdomen that marks the former attachment of the umbilical cord to the fetus; also called the navel

uremia - the accumulation of toxic levels of urea and other nitrogenous waste products in the blood

ureter - one of two tubes that connect the kidney with the urinary bladder

urethra - the duct from the urinary bladder to the exterior of the body; conveys urine in females and urine and semen in males

urinary bladder - a hollow, muscular organ, situated in the pelvic cavity posterior to the pubic symphysis

urobilinogenuria - the presence of urobilinogen in the urine

urogenital triangle - region of the pelvic floor below the symphysis pubis, bounded by the symphysis pubis and ischial tuberosities, and containing the external genitalia

urology - the specialized branch of medicine that deals with the structure, function, and diseases of the male and female urinary systems, as well as the male reproductive system

urticaria - a skin reaction to certain foods, drugs, or other substances to which a person may be allergic; hives

uterine tube - a duct that transports ova from the ovary to the uterus; also called the oviduct or Fallopian tube

uterosacral ligament - a fibrous band of tissue extending from the cervix of the uterus laterally to attach to the sacrum

uterovesical pouch - a shallow pouch formed by reflection of peritoneum from the anterior surface of the uterus, at the junction of the cervix and the body, to the posterior surface of the urinary bladder

uterus - hollow, muscular organ in females; it is the site of menstruation, implantation, fetal development, and labor; also called the womb

utricle - larger of two divisions of the membranous labyrinth located inside the vestibule of the inner ear; contains a receptor organ for static equilibrium

uvea - the three structures that together make up the vascular tunic of the eye

uvula - a soft, fleshy mass, especially the V-shaped pendant part, hanging down from the soft palate
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vacuole - membrane-bound organelle that, in animal cells, frequently functions in temporary storage or transport of materials

vagina - a muscular, tubular organ that leads from the uterus to the vestibule, situated between the urinary bladder and the rectum of the female

valvular stenosis - narrowing of a heart valve, usually the bicuspid (mitral) valve

varicocele - a twisted vein; especially, the accumulation of blood in the veins of the spermatic cord

varicose - pertaining to an unnatural swelling, as in the case of a varicose vein

vasa recta - extensions of the efferent arteriole of a juxtaglomerular nephron that run alongside the loop of the nephron (Henle) in the medullary region

vasa vasorum - blood vessels that supply nutrients to larger arteries and veins

vascular - pertaining to or containing many blood vessels

vasectomy - a means of sterilization of males in which a portion of each ductus (vas) deferens is removed

vasoconstriction - the decrease in size of the lumen of a blood vessel, caused by contraction of smooth muscle in the wall of the vessel

vasodilation - an increase in the size of the lumen of a blood vessel caused by relaxation of the smooth muscle in the wall of the vessel

vasomotion - intermittant contraction and relaxation of smooth muscle of the metarterioles and the precapillary sphincters; it results in intermittent blood flow

vasomotor center - a cluster of neurons in the medulla that controls the diameter of blood vessels, especially arteries

vena cava - one of two large veins that open into the right atrium, returning to the heart all of the deoxygenated blood from the systemic circulation, except the coronary circulation

venesection - opening of a vein for withdrawal of blood

ventral - pertaining to the anterior or front side of the body; opposite of dorsal

ventral ramus - the anterior branch of a spinal nerve, containing sensory and motor fibers to the muscles and skin of the anterior surface of the head, neck, trunk, and the extremities

ventricle - a cavity in the brain or an inferior chamber of the heart

ventricular fibrillation - asynchronous ventricular contractions that result in cardiovascular failure

venule - a small vein that collects blood from capillaries and delivers it to a vein

vermiform appendix - the twisted, coiled tube attached to the cecum

vermilion - area of the mouth where the skin on the outside meets the mucous membrane on the inside

vermis - a central constricted area of the cerebellum, separating the cerebellar hemispheres

vertebral canal - the cavity within the vertebral column formed by the vertebral foramina of all the vertebrae and containing the spinal cord; also called the spinal canal

vertigo - a sensation of spinning or movement

vesicle - small bladder or sac, containing liquid

vestibular membrane - membrane that separates the cochlear duct from the scala vestibuli

vestibule - a small space or cavity at the beginning of a canal, especially the inner ear, larynx, mouth, nose, and vagina

villus - a projection of the intestinal mucosal cells, containing connective tissue, blood vessels, and a lymphatic vessel; functions in absorption of end products of digestion; plural, villi

viscera - the organs inside the ventral body cavity; singular, viscus

visceral - pertaining to the organs or to the covering of an organ

visceroceptor - receptor that provides information about the body's internal environment

viscosity - the state of being sticky or thick

vitiligo - patchy, white spots on the skin, due to partial or complete loss of melanocytes

vitreous body - a soft, jellylike substance filling the vitreous chambers of the eyeball, lying between the lens and the retina

vulva - collective designation for the external genitalia of the female; also called the pudendum
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Wallerian degeneration - degeneration of the portion of the axon and the myelin sheath of a neuron, distal to the site of injury

wheal - elevated lesion of the skin

white ramus communicans - the portion of a preganglionic sympathetic nerve fiber that branches away from the anterior ramus of a spinal nerve to enter the nearest sympathetic trunk ganglion
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xiphoid - sword-shaped; the inferior portion of the sternum

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NO ENTRIES

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zona fasciculata - middle zone of the adrenal cortex; consists of cells arranged in long, straight cords; secretes glucocorticoid hormones

zona glomerulosa - outer zone of the adrenal cortex, directly under the connective tissue covering; consists of cells arranged in arched loops or round balls; secretes mineralocorticoid hormones

zona pellucida - a gelatinous glycoprotein layer internal to the corona radiata; surrounds a secondary oocyte

zona reticularis - inner zone of the adrenal cortex; consists of cords of branching cells that secrete sex hormones, primarily androgens

zygote - a single cell resulting from union of a male and female gamete; a fertilized ovum

zymogenic - one of the cells of a gastric gland that secretes the principal gastric enzyme precursor, pepsinogen; also called a peptic cell

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Last Updated: 30 Aug 2018