The Large Intestine - E. coli , produce vitamins (including...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
The Large Intestine The large intestine is made up by the colon, cecum, appendix , and rectum. Material in the large intestine is mostly indigestible residue and liquid. Movements are due to involuntary contractions that shuffle contents back and forth and propulsive contractions that move material through the large intestine. The large intestine performs three basic functions in vertebrates: 1) recovery of water and electrolytes from digested food; 2) formation and storage of feces; and 3) microbial fermentation: The large intestine supports an amazing flora of microbes. Those microbes produce enzymes that can digest many of molecules indigestible by vertebrates. Secretions in the large intestine are an alkaline mucus that protects epithelial tissues and neutralizes acids produced by bacterial metabolism. Water, salts, and vitamins are absorbed, the remaining contents in the lumen form feces (mostly cellulose, bacteria, bilirubin). Bacteria in the large intestine, such as
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: E. coli , produce vitamins (including vitamin K) that are absorbed. Regulation of Appetite The hypothalamus in the brain has two centers controlling hunger. One is the appetite center, the other the satiety center. Gastrin , secretin , and cholecystokinin are hormones that regulate various stages of digestion. The presence of protein in the stomach stimulates secretion of gastrin, which in turn will cause increased stomach acid secretion and mobility of the digestive tract to move food. Food passing into the duodenum causes the production of secretin, which in turn promotes release of alkaline secretions from the pancreas, stops further passage of food into the intestine until the acid is neutralized. Cholecystokinin (CCK) is released from intestinal epithelium in response to fats, and causes the release of bile from the gall bladder and lipase (a fat digesting enzyme) from the pancreas....
View Full Document

Ask a homework question - tutors are online