Medical Terminology
Glossary
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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; comprises sugar subLETTERs; usually has the formula (CH2O)n
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 - compression of the heart due to excessive fluid or blood in the pericardial sac; could result in cardiac failure
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 resuscit... - 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 taillike collection of roots of spinal nerves at the inferior end of the spinal canal
caudal - pertaining to any taillike 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 - tendonlike, 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 nondividing 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 semifluid 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 hairlike 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 - semifluid portion of cytoplasm in which organelles and inclusions are suspended and solutes are dissolved—also called intracellular fluid