Digestion and absorption

MacFarlane, N. G. (2018) Digestion and absorption. Anaesthesia and Intensive Care Medicine, 19(3), pp. 125-127. (doi: 10.1016/j.mpaic.2018.01.001)

Abstract

Carbohydrates are digested by salivary and pancreatic amylases to di-, tri- and oligosaccharides, and then to monosaccharides by enzymes on the wall of the small intestine to allow them to be absorbed. Proteins are absorbed as amino acids and small peptides that are broken down to amino acids within the cells. Monosaccharides and amino acids pass into the liver via the portal vein. Fats are digested and absorbed as free fatty acids and glycerides that are then mostly reconstituted as triglycerides in the mucosal cells of the small intestine. They combine with phospholipids and a protein to form chylomicrons, which pass via the lymphatics and the thoracic duct into the systemic circulation. Fatty acids are re-esterified and stored as triglycerides in adipose tissue or oxidized for energy. Water is passively absorbed due to the osmotic gradient that results mainly due to the active absorption of sodium ions.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacFarlane, Professor Niall
• Authors: MacFarlane, N. G.
• College/School: College of Medical Veterinary and Life Sciences > School of Life Sciences
• Journal Name: Anaesthesia and Intensive Care Medicine
• Publisher: Elsevier
• ISSN: 1472-0299
• ISSN (Online): 1878-7584
• Published Online: 04 February 2018
• Copyright Holders: Copyright © 2018 Elsevier Ltd.
• First Published: First published in Anaesthesia and Intensive Care Medicine 19(3):125-127
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher