COLON

in Greek or Latin verse, a rhythmic measure of lyric metre (lyric in the sense of verse that is sung rather than recited or chanted) with a recognizable recurring pattern. The word colon is also occasionally used of prose to describe the division (by sense or rhythm) of an utterance that is smaller and less independent than a sentence but larger and less dependent than a phrase. in physiology, that segment constituting most of the length of the large intestine in mammals. The term is often used synonymously with large intestine or in reference to a corresponding region of the vertebrate gut. The human colon extends from the end of the small intestine and cecum up the right side of the abdomen (ascending colon), across to the left side (transverse colon), down the left side (descending colon), and loops (sigmoid flexure, or sigmoid colon) to join the rectum. In humans, the colon has no digestive function. Its purpose is to lubricate waste products, absorb remaining fluids and salts, and store waste products until they are ready to be passed from the body. Most absorption occurs in the ascending and transverse regions, where the liquid material received from the small intestine is dehydrated to form a fecal mass. The inner wall of the colon consists of a mucous membrane that absorbs the fluids and gives off mucus to lubricate the waste materials. The deeper muscle layer is composed of circular and longitudinal muscles. Circular muscles produce the mild churning and mixing motions of the intestine, while the longitudinal ones create the strong massive muscle contractions that actually move the feces. Medical problems associated with the colon range from constipation, diarrhea, gas discomfort, and colitis (inflammation of the colon) to the more serious megacolon (enlarged colon) and cancer. See also large intestine.