- large intestine
intestine (def. 3).[1855-60]
* * *End section of the intestine.It is about 5 ft (1.5 m) long, is wider than the small intestine, and has a smooth inner wall. In the first half, enzymes from the small intestine complete digestion, and bacteria produce many B vitamins and vitamin K. Over 24–30 hours, churning movements break down tough cellulose fibres and expose chyme to the colon's walls, which absorb water and electrolytes; absorption is its main function, along with storing fecal matter for expulsion. The more vigorous "mass movement" (gastrocolic reflex) occurs only two or three times a day to propel waste material toward the anal canal. Common afflictions include ulcerative colitis, diverticulosis (see diverticulum), polyps, and tumours.
* * *posterior section of the intestine, consisting typically of four regions: the cecum, colon, rectum, and anus. The term colon is sometimes used to refer to the entire large intestine.The large intestine is wider and shorter than the small intestine (approximately 1.5 metres, or 5 feet, in length as compared with 6.7 to 7.6 metres, or 22 to 25 feet, in length for the small intestine) and has a smooth inner wall. In the proximal, or upper, half of the large intestine, enzymes from the small intestine complete the digestive process, and bacteria produce B vitamins (B12, thiamin, and riboflavin) as well as vitamin K. The primary function of the large intestine, however, is absorption of water and electrolytes from digestive residues (a process that usually takes 24 to 30 hours) and storage of fecal matter until it can be expelled. Churning movements of the large intestine gradually expose digestive residue to the absorbing walls. A progressive and more vigorous type of movement known as the gastrocolic reflex, which occurs only two or three times daily, propels the material toward the anus.Common afflictions of the large intestine include inflammation, such as colitis (ulcerative colitis); diverticulosis (diverticulum); and abnormal growths, such as benign or malignant tumours.
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