Medical Glossary Index:

V

Vaccination- a form of immunization in which killed or weakened microorganisms are placed into the body, where antibodies against them are developed; if the same types of microorganisms enter the body again, they will be destroyed by the antibodies

Vaccine- a preparation of weakened microorganisms given to create resistance to a certain disease

Vacuum aspiration- removal of the contents of the uterus using a suction device

Vacuum extraction- a technique used to facilitate childbirth using a suction device to help move the baby through the birth canal

Vagina- the muscular passage connecting the uterus with the outside genitals; a component of the female reproductive system

Vaginismus- an involuntary muscle spasm at the opening of the vagina when sexual intercourse is attempted; can be quite painful and may make sexual intercourse nearly impossible

Vaginitis- inflammation of the vagina, which can be the result of infection, aging, a hormone deficiency, or a foreign object (such as a tampon)

Valve- a structure that allows fluid flow in only one direction

Valvotomy- surgical correction of a narrowed heart valve

Valvular heart disease- a heart valve defect

Valvuloplasty- reconstruction or repair of a narrowed heart valve

Varicella- the medical term for chickenpox

Varices- enlarged or twisted blood or lymph vessels

Varicocele- the appearance of varicose veins around the testicles; commonly occurs and is harmless, but may cause discomfort

Varicose veins- enlarged, twisted veins just below the surface of the skin, caused by defective valves in the veins

Variola- another term for smallpox

Vascular- pertaining to blood vessels

Vasculitis- inflammation of blood vessels

Vas deferens- a thin tube that stores and transports sperm

Vasectomy- a usually permanent method of sterilization in which the tubes carrying sperm from the testicles (the vas deferens) are cut and tied off; as a result, the semen will no longer contain sperm

Vasoconstriction- narrowing of blood vessels

Vasodilation- widening of blood vessels

Vasovagal attack- a sudden slowing of the heart, causing fainting

VD- see Venereal disease

Vein- a blood vessel that carries blood toward the heart

Venereal disease- any disease that is usually spread through sexual intercourse or genital contact

Venipuncture- piercing of a vein with a hollow needle to inject fluid or withdraw blood

Venography- an X-ray procedure for viewing veins

Venom- a poisonous substance produced by certain animals

Ventilation- the process through which oxygen and carbon dioxide are exchanged between the lungs and the air; also refers to the use of a machine to carry out this process in someone who cannot breathe on his or her own

Ventilator- a machine used to take over breathing when a person cannot breathe on his or her own

Ventricle- a small cavity or chamber; there are four ventricles in the brain that circulate cerebrospinal fluid through it, and two in the heart that pump blood throughout the body

Ventricular fibrillation- rapid, irregular contractions of the heart

Ventricular septal defect- a hole in the wall that separates the two lower chambers of the heart (called the ventricles)

Vernix- the thick, greasy substance that covers the skin of a newborn baby

Version- a shift in the position of the fetus inside of the uterus, either occurring naturally or as performed by a doctor to facilitate delivery

Vertebra- any one of the 33 bones that make up the spine

Vertebral arteries- a pair of arteries running up the neck to supply the brain
with blood

Vertebrobasilar insufficiency- episodes of dizziness and weakness caused by insufficient blood flow to the brain

Vertex presentation- the usual, head-first presentation of the fetus during delivery

Vertigo- the feeling that one or one's surroundings are spinning

Very low-density lipoprotein- a class of blood proteins, a high level of which is associated with coronary heart disease

Vesicle- a small skin blister, or any sac in the body, that contains fluid

Vestibular glands- two small glands located at the opening of the vagina that secrete a lubricating fluid during sexual stimulation

Villi- the millions of fingerlike projections on the lining of the small intestine that
aid in the absorption of food

Viral- a term describing something related to or caused by a virus

Viremia- the presence of viruses in the blood

Virilization- the process by which a woman develops male characteristics;
caused by overproduction of male sex hormones

Virulence- the relative ability of an organism to cause disease

Virus- the smallest known disease-causing microorganism; viruses are very simple in structure and can only multiply when they are inside the cell of another organism

Visual acuity- a measure of the sharpness of a person's vision

Visual field- the area on both sides that can be seen while looking straight ahead

Vital sign- any sign, such as a pulse, that indicates that a person is alive

Vitamin A- a vitamin essential for normal growth and development of the body (most notably the bones and teeth), protection of mucous membranes from infection, normal vision, and healthy skin and hair

Vitamin B complex- a group of vitamins including thiamine, niacin, riboflavin, pantothenic acid, pyridoxine, biotin, and folic acid; plays a variety of important roles in the body, including in hormone production, metabolism, and functioning of the nerves, muscle, heart, and digestive system

Vitamin B6- a vitamin that plays an important role in the breakdown and use of energy sources, production of red blood cells and antibodies, and normal functioning of the nervous system

Vitamin B12- a vitamin that is essential to the production of DNA (the genetic material in cells) and red blood cells and in the functioning of the nervous system

Vitamin C- a vitamin with many essential roles, including in maintaining healthy bones, teeth, gums, ligaments, and blood vessels and in the immune system's
response to infection

Vitamin D- a vitamin that plays a role in the absorption of calcium by the
intestines and is essential for healthy bones and teeth

Vitamin E- a vitamin that protects tissues from damage by oxygen free radicals, helps to form red blood cells, maintains the function of enzymes, and maintains cell structure

Vitamin K- a vitamin that is essential for normal blood clotting and the body's absorption of calcium

Vitamins- complex substances that are necessary in small amounts to maintain health and ensure proper development and functioning of the body

Vitiligo- a condition in which patches of skin on the body lose their color; thought to be caused by the immune system attacking the skin tissues, causing the absence of melanin

Vitreous humor- the clear, watery fluid that fills the cavity of the eye behind the lens

VLDL- see Very low-density lipoprotein

Vocal cords- two strips of tissue in the voice box that have the ability to produce sound when air passing through them causes the tissues to vibrate

Volvulus- twisting and obstruction of an area of intestine

Von Willebrand's disease- a genetic disorder characterized by excessive bleeding

V/Q lung scans- images produced by radionuclide scanning of the lungs; used to help diagnose a pulmonary embolism

Vulva- the outer, visible portion of the female genitals

Vulvitis- inflammation of the vulva

Vulvovaginitis- inflammation of the vulva and vagina