Medical Terminology Glossary

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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