V - Glossary of Terms

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V - Glossary of Terms

vacuole	(vak-yoo'-ol) A small space or cavity within the cytoplasm of a cell.
vagina	(va-ji´na) A tubular organ leading from the uterus to the vestibule of the female reproductive tract that receives the male penis during coitus.
valence electron	An electron in the outermost shell.
valgus	[val-guhs] Denoting a deformity in which the distal part of a limb is displaced or twisted away from the midline of the body (e.g. knock kneed) [see also varus]
vallate papillae	(val´-at pa-pil´e) The largest papillae on the surface of the tongue. They are arranged in an inverted V-shaped pattern at the posterior portion of the tongue.
valsalva maneuver	(val-saI'va) (Antonio Mario Valsalva, Italian anatomist, 1666-1723) Act of forcing a deep breath against closed glottis. This is achieved by a straining action, as if trying to move the bowels, without blowing out the cheeks or filling the pharynx.
valvulae conniventes	Circular folds of the small bowel.
variable aperture collimator	A box shaped device containing a radiographic beam-defining system. It is the device most often used to decline the size and shape of a radiographic beam.
varices	(var'i-sez) Permanently dilated and tortuous veins; varicosities.
varicose	(var'i-kos) Irregularly dilated; enlarged and tortuous; pertaining to a venous varix or varices.
varix	(var-iks) Permanently dilated and tortuous veins; varicosities.
varus	(ˈvar-əs) Denoting a deformity in which the distal part of a limb is turned inwards towards the midline of the body (e.g. bow-legged) [see also valgus]
vas	(vas) Vessel or duct; specifically, a blood, spermatic, or lymph vessel.
vasculitis	Inflammation of a vessel.
vasectomy	(va-sek´to-me) Surgical removal of portions of the ductus deferentia to induce infertility.
vasoconstriction	(va´´zo-kon-strik´shun) Narrowing of the lumen of blood vessels due to contraction of the smooth muscles in their walls.
vasodilation	(va´´zo-di-la´shun) Widening of the lumen of blood vessels due to relaxation of the smooth muscles in their walls.
vasomotor center	(va´´zo-mo´tor) A cluster of nerve cell bodies in the medulla oblongata that controls the diameter of blood vessels. It is therefore important in regulating blood pressure.
VDT	Abbreviation for video display terminal.
vector	A quantity or measurement that has magnitude, unit, and direction.
vein	(v-an) A blood vessel that conveys blood toward the heart.
velocity (v)	The rate of change of an object's position with time; speed.
vena	(ve'nah) Vein
vena cava	(ve´na ka´va) One of two large vessels that return deoxygenated blood to the right atrium of the heart.
venogram	(ven'o-gram) Radiograph of veins filled with contrast medium; a phlebogram.
venography	(ve-nog'ra-fe) Radiologic examination of veins during injection of radiopaque solution.
ventilation	(ven´´ti-la´shun) Breathing; the process of moving air into and out of the lungs.
ventrad	(ven'trad) Situated or directed toward abdomen or anterior aspect of body; ventrally.
ventral	(ven´tral) Toward the front or facing surface; the opposite of dorsal; also called inferior.
ventricle	(ven´tri-k'l) A cavity within an organ; especially those cavities in the brain that contain cerebrospinal fluid and those in the heart that contain blood to be pumped from the heart.
ventriculography	(ven-trik"u-log'ra-fe) Radiographic examination of brain following injection of radioparent medium into ventricles; pneumoventriculography.
venule	(ven´yool) A small vessel that carries venous blood from capillaries to a vein.
vermiform	(ver'mi-form) Resembling a worm; as vermiform appendix or cecum.
vermis	(ver´mis) The coiled middle lobular structure that separates the two cerebellar hemispheres.
vertebral canal	(ver´te-bral) The tubelike cavity extending through the vertebral column that contains the spinal cord; also called the spinal canal.
vertex	(ver'teks) Top or highest part of head.
verticomental	(verti-ko-men'tal) Pertaining to vertex and chin; as a verticomental projection of facial bones.
verticosubmental	(ver'ti-ko-sub-men'tal) Pertaining to vertex and region of throat below chin; as a verticosubmental projection of petrosae.
vertigo	(ver´ti-go) A feeling of movement or loss of equilibrium.
vesicle	(ves'i-k'l) Fluid-containing cavity or sac; blister.
vestibular window	See oval window.
vestibule	(ves´ti-byool) A space or cavity at the entrance to a canal, especially that of the nose, inner ear, or vagina.
video display terminal	A monitor similar to a television screen.
vidicon	The television-camera tube most often used in television fluoroscopy.
vignetting	A reduction in brightness at the periphery of the image.
villi	(vil'i) Minute, threadlike processes that project from specialised mucous membrane, as from mucosa of small intestine.
villus	(vil´us) A minute projection that extends outward into the lumen from the mucosal layer of the small intestine.
Virchow's plane	(ver'koz) (Rudolf Virchow, German pathologist, 1821-1902). See infraorbitomeatal line.
virulent	(vir´u-lent) Pathogenic; able to cause disease.
virus	One of a group of minute infectious agents characterised by a lack of independent metabolism and by the ability to reproduce only within living host cells.
viscera	(vis´er-a) The organs within the abdominal or thoracic cavities.
visceral	(vis´er-al) Pertaining to the membranous covering of the viscera.
visceral peritoneum	(per´´it-o-ne´um) A serous membrane that covers the surfaces of abdominal viscera.
visceral pleura	(ploor´a) A serous membrane that covers the surfaces of the lungs.
visceroceptor	(vis´´er-o-sep´tor) A sensory receptor located within body organs that responds to information concerning the internal environment.
viscid	(vis'id) Having a gelatinous or stick consistency; adherent; viscous.
visceroptosis	(vis"er-op-ta'sis) Falling or downward displacement of abdominal organs.
viscosity	(vis-kos'i-te) State or quality of being thick and sticky; viscid; gluey, glutinous.
viscous	Thick, sticky.
viscus	(vis'kus) Internal organ, such as heart. kidney, or stomach.
visible light	The radiant energy in the electromagnetic spectrum that is visible to the human eye.
vitiate	(vish'i-at) To render faulty or defective; to impair quality of; to contaminate; to make impure, as air by electrical corona or by products of respiration.
vitreous humor	(vit´re-us hyoo´mer) The transparent gel that occupies the space between the lens and retina of the eyeball.
Volkmann's canal	(f-olk´manz) See perforating canal.
volt (V)	The SI unit of electric potential and potential difference.
voltage ripple	A way to characterise voltage waveforms.
voltaic pile	A stack of copper and zinc plates that produces an electric current; a precursor of the modern battery.
voluntary	(vol'un-ter'e) Proceeding in obedience to will; acting according to choice.
vomit	(vom'it) Spontaneous expulsion of contents of stomach by mouth; also, the vomited matter.
vomitus	(vom'i-tus) Matter ejected from stomach through mouth.
voxel	A three-dimensional pixel; volume element.
vulva	(vul´vua) The external genitalia of the female that surround the opening of the vagina.

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