Columbia Encyclopedia

Search results

500 results found

nail, in anatomy

(Encyclopedia)nail, in anatomy, the horny outgrowth shielding the tip of the finger and the toe in humans and most other primates. The nail consists of dead cells pushed outward by dividing cells in the root, a fol...

varicose vein

(Encyclopedia)varicose vein, superficial vessel that is abnormally lengthened, twisted, or dilated, seen most often on the legs and thighs. Varicose veins develop spontaneously, and are usually attributed to a here...

vegetarianism

(Encyclopedia)vegetarianism, theory and practice of eating only fruits and vegetables, thus excluding animal flesh, fish, or fowl and often butter, eggs, and milk. In a strict vegetarian, or vegan, diet (i.e., one ...

martial arts

(Encyclopedia)martial arts, various forms of self-defense, usually weaponless, based on techniques developed in ancient China, India, and Tibet. In modern times they have come into wide use for self-protection, as ...

streptococcus

(Encyclopedia)streptococcus strĕpˌtəkŏkˈəs [key], any of a group of gram-positive bacteria, genus Streptococcus, some of which cause disease. Streptococci are spherical and divide by fission, but they remain ...

Rh factor

(Encyclopedia)Rh factor, protein substance present in the red blood cells of most people, capable of inducing intense antigenic reactions. The Rh, or rhesus, factor was discovered in 1940 by K. Landsteiner and A. S...

apheresis

(Encyclopedia)apheresis hēˌməfĕrˈəsĭs [key], any procedure in which blood is drawn from a donor or patient and a component (platelets, plasma, or white blood cells) is separated out, the remaining blood comp...

blue baby

(Encyclopedia)blue baby, infant born with a congenital heart defect that causes a bluish coloration of the skin as a result of cyanosis (deoxygenated blood). The color is most noticeable around the lips and at the ...

bloodletting

(Encyclopedia)bloodletting, also called bleeding, practice of drawing blood from the body in the treatment of disease. General bloodletting consists of the abstraction of blood by incision into an artery (arterioto...

isobar

(Encyclopedia)isobar īˌsəbărˈĭk [key], line drawn on a weather map through points of equal atmospheric pressure. Isobars are used to define cyclones (low-pressure regions) and anticyclones (high-pressure regi...