Digestion and Absorption of Organic Nutrients

Digestion and - Dr Kennon M Garrett GI-40 DIGESTION AND ABSORPTION OF ORGANIC NUTRIENTS Learning Objectives 1 Describe the digestion and absorption

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Dr. Kennon M. Garrett GI-40 DIGESTION AND ABSORPTION OF ORGANIC NUTRIENTS Learning Objectives 1. Describe the digestion and absorption of carbohydrates. 2. Describe the digestion and absorption of proteins. 3. Describe the activation of pancreatic proteolytic enzymes. 4. Describe the digestion and absorption of fats. 5. Describe the absorption of vitamins. Dr. Kennon M. Garrett GI-41 I. Introduction A. Digestion: breakdown of macromolecules to constituents that can then be absorbed B. Absorption: transport across the epithelium Review of epithelial transport Dr. Kennon M. Garrett GI-42 II. Absorption from the mouth and stomach A. Absorption is by simple diffusion B. Limited to amphiphilic solutes (solutes with some solubility in both water and fat) e.g. nitroglycerin, alcohol and aspirin III. The small intestine Most of the absorption of organic nutrients occurs in the small intestine. A. Expansion of the digestive/absorptive surface The lumenal surface of the small intestine is specialized to provide a large surface area for digestion and absorption. Specializations include: 1) large folds of the mucosa, muscularis and submucosa, 2) fingerlike projections of the mucosa (villi) and 3) projections of the lumenal membrane of enterocytes (microvilli). Together these increase the surface area ~ 600 fold to about 200 m 2 . Dr. Kennon M. Garrett GI-43 B. Localization of absorption Some nutrients (e.g. carbohydrate, protein and lipid) are efficiently absorbed along the entire length of the small intestine with the greatest absorption in the duodenum followed by the jejunum and the smallest absorption occurs in the ileum. Absorption of others is restricted to certain regions of the small intestine. For instance, specialized absorptive systems for iron are found only in the duodenum while those for vitamin B 12 and bile salts are restricted to the ileum. IV. Digestion and absorption of carbohydrates A. Digestion Carbohydrates often account for as much as 50% of caloric intake. Complex carbohydrates (starches) and dietary disaccharides ( e.g. sucrose) must be digested to monosaccharides in order to be absorbed. Complex carbohydrates are first digested in the lumen of the GI tract by salivary to be absorbed....
View Full Document

This note was uploaded on 10/01/2011 for the course PSYO 5016 taught by Professor Staff during the Fall '11 term at The University of Oklahoma.

Page1 / 11

Digestion and - Dr Kennon M Garrett GI-40 DIGESTION AND ABSORPTION OF ORGANIC NUTRIENTS Learning Objectives 1 Describe the digestion and absorption

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online