The Small Intestine

The Small Intestine - ), lipases , nucleases , and...

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

View Full Document Right Arrow Icon
The Small Intestine, Liver, Gallbladder and Pancreas Nearly all chemical digestion and nutrient absorption occurs in the small intestine. The cells of the duodenum also secrete paracrine hormones that regulate gastric secretions and the release of bile from the gallbladder. Cholecystokinin , secretin , and gastric inhibitory peptide inhibit gastric secretions while increasing the secretion of chemicals into the duodenum. The liver is a multifunctional organ. It produces bile, which aids in fat digestion; it detoxifies and stores nutrients that are absorbed from the stomach and small intestine; and it produces many important blood plasma proteins. The gallbladder stores and concentrates bile produced by the liver. The pancreas is a mixed gland and is also multifunctional. As an exocrine gland, the pancreas produces and secretes most of the enzymes necessary for chemical digestion. These include the proteinases (trypsinogen , chymotrypsinogen and peptidases
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ), lipases , nucleases , and sugarases (amylase and maltase ). The pancreatic juices secreted into the duodenum also include HCO 3-which neutralizes the HCl in the chyme. The pancreas also secretes insulin and glucagon into the blood. The Large Intestine The large intestine reabsorbs water, electrolytes (e.g., Na + , K + , Mg 2+ , Ca 2+ ) and bile. It also absorbs ingested vitamin K . Some normally present bacteria within the large intestine can also produce vitamin K. After reabsorption, the remaining material is known as feces. Approximately 75% of an ordinary sample of human feces is water. Of the remaining 25%, 1/3 is dead bacteria. Another 1/3 of the remaining quarter is indigestible food, such as cellulose . Stretching of the rectum stimulates defecation-- the muscularis layer contracts and the internal anal sphincter relaxes. However, defecation only occurs if the external anal sphincter is voluntarily relaxed....
View Full Document

This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

Ask a homework question - tutors are online