ulcer. A discontinuity of the surface membrane, the epithelium. An ulcer may occur over the skin, or inside as over the lining of the stomach or intestine (the mucous membrane).

Universal precautions. A set of rules to minimize transmission of disease from a patient to a doctor.

uremia. Increased urea in the blood, that occurs in kidney failure.

urethra. A tube that leads out from the urinary bladder, and discharges urine. In the male the urethra lies deep in the penis. In the female the urethra is short and lies just above the vaginal orifice.

urinary bladder. A sac that stores urine. The urinary bladder is situated in the pelvic cavity.

urine. Fluid produced by the kidneys. Urine contains urea and other wastes that filter out from the kidneys. The urine flows from the kidneys, via the ureters into the urinary bladder, where it is stored until it is passed out through the urethra.

uterus. The womb. It is one of the female genital organs, and lies in the pelvic cavity in the midline, between the rectum and the urinary bladder.

ultrasonography. A technique of imaging parts of the human body with a machine that uses sound waves. Ultrasound: the high-frequency sound waves used for this purpose. Ultrasonogram. The picture produced by an ultrasound machine.


vancomycin. A glycopeptide antibiotic.

varices (sing=varix). Dilated veins. Such dilatations of veins occur a. in the esophagus from portal hypertension, b. in the legs, as varicose veins, c. in the anal canal as hemorrhoids, and d. in the scrotum as a varicocele.

vasopressin (=antidiuretic hormone, ADH) A hormone produced by the pituitary gland, it helps the kidneys retain urine and also increases the blood pressure.

vein. The tubular organs that carry deoxygenated blood back from the organs to the heart.

vena cava. There are two vena cavae: the superior and the inferior. The superior vena cava is the great vein that enters the right side of the heart, carrying blood from the upper body. The inferior vena cava also enters the right heart, carrying blood from the lower body.

ventricle <L ventriculus=belly> In the heart, one of the two chambers, the right ventricle and the left ventricle, that pump blood out of the heart. In the brain, one of four chambers (left lateral ventricle, right lateral ventricle, third ventricle, fourth ventricle) containing cerebrospinal fluid.

vermiform appendix. appendix

vertebra. One of the 33 bones that comprise the vertebral column, or spine.

Vesalius, Andreas. 1514–64. Belgian anatomist. See biographical dictionary.

vestibular nerve. The nerve that leads from the semicircular canals to the brain, and is part of the pathway that controls balance and posture.

visual acuity test. This eye chart test measures how well you see at various distances.


window period. In AIDS, the duration in which the patient tests negative for HIV infection, but is able to transmit disease. (Article on AIDS)

womb. The uterus.


X chromosome. See chromosome.

xanthines. a class of drugs. Caffeine, found in coffee (and in tea) is a xanthine.

xiphisternum. The lowermost end of the sternum (the breastbone).

xenotransplantation. A transplant using a donor from a different species. See transplant.

xylometazoline. A drug used as a nasal decongestant.


Y chromosome. See chromosome

yellow fever. A viral illness characterized by fever and jaundice. The disease is transmitted by the bite of the mosquito Aedes aegypti, and tends to occur in epidemics. As for most viral illnesses, there is no specific treatment.


zidovudine. A drug used in AIDS. (Article on AIDS)

zygote. The fertilized ovum.