von Hippel-Lindau syndrome A genetic disease that is characterized by hemangioblastomas (benign blood vessel tumors) in the brain, spinal cord, and retina; kidney cysts, and kidney cancer (renal cell carcinoma); pheochromocytomas (benign tumors of adrenal-like tissue); and endolymphatic sac tumors (benign tumors of the labyrinth in the inner ear). Abbreviated VHL syndrome. The brain hemangioblastomas…
vomitus See vomit.
vomiting of pregnancy, pernicious See hyperemesis gravidarum.
vomiting in pregnancy, excess See hyperemesis gravidarum.
vomit 1 Matter from the stomach that is ejected in tandem with symptoms of nausea. When vomit is reddish or coffee-ground colored, it indicates serious internal bleeding. Also known as vomitus. 2 To expel vomit. Also known as emesis.
volvulus Abnormal twisting of a portion of the gastrointestinal tract, usually the intestine, which can impair blood flow. Volvulus can lead to gangrene and death of the involved segment of the gastrointestinal tract, intestinal obstruction, perforation of the intestine, and peritonitis. The stomach, small intestine, cecum, and sigmoid colon are all subject to volvulus. Malrotation…
voluntary Done in accordance with the conscious will of the individual. The opposite of voluntary is involuntary. The terms voluntary and involuntary apply to the human nervous system and its control over muscles. The nervous system is divided into two parts: somatic and autonomic. The somatic nervous system operates the skeletal muscles, which are under…
volume, stroke See stroke volume.
volar Pertaining to the palm or the sole. For example, the volar surface of the forearm is the portion of the forearm that is on the same side as the palm of the hand.
void To urinate. The term void is also sometimes used to indicate the elimination of solid waste (defecation).
vocal cord One of the two small bands of muscle that form a V-shape within the larynx. When a person breathes, the vocal cords relax, and air moves through the space between them without making a sound. When a person talks or sings, the vocal cords tighten up and move closer together. Air from the…
vitreous humor A clear, jelly-like substance that fills the middle of the eye.