Medical Terminology
Glossary
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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
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