05 Digestive System

05 Digestive System - The Digestive System HNFE 3025 Fall...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
The Digestive System HNFE 3025 Fall 2009
Background image of page 1

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

View Full DocumentRight Arrow Icon
Digestion and Absorption Takes place in GI tract which begins at the mouth and ends at the anus. Includes oral cavity, esophagus, stomach, small intestine and large intestine. The GI tract is dependent on secretions from the stomach and intestinal cells as well as from accessory organs – salivary glands, liver, pancreas and gallbladder. 2
Background image of page 2
3 Fig. 2-1, p. 34
Background image of page 3

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

View Full DocumentRight Arrow Icon
4 Table 2-1, p. 36
Background image of page 4
Digestion To break down proteins to constituent amino acids To break down carbohydrates to simple monosaccharides (glucose, fructose…) To break down lipids (triacylglycerols, cholesterol esters, phospholipids) to smaller absorbable constituents To release minerals and vitamins from foods so that they can be absorbed Most digestion occurs in small intestine Primarily occurs in the lumen and at the brush border 5
Background image of page 5

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

View Full DocumentRight Arrow Icon
Absorption Takes place primarily in si Mechanism of absorption depends on: Solubility (fat vs. water) Concentration or electrical gradient Size of molecule Stomach can absorb ethanol and some short chain fatty acids Colon can absorb water and electrolytes (Na + , K + , etc.) as well as short chain fatty acids (acetic, propionic, butyric acids) produced by colonic bacteria. 6
Background image of page 6
7 Fig. 2-3, p. 36
Background image of page 7

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

View Full DocumentRight Arrow Icon
The Esophagus Moves bolus from oral cavity to stomach Voluntary (upper) and involuntary (lower) muscular contractions Peristalsis Lower esophageal sphincter controlled by neural and hormonal mechanisms 8
Background image of page 8
Peristalsis Primary peristaltic wave Forces the bolus down the esophagus and into the stomach in a wave lasting about 10 seconds. Wave travels down to the stomach even if the bolus of food descends faster or slower than the wave. Secondary peristaltic wave When bolus is poorly lubricated and descends slower than the primary wave, stretch receptors in the esophageal lining are stimulated and a local reflex response causes secondary waves to propel the bolus until it enters the stomach.
Background image of page 9

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

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/23/2010 for the course HNFE 3025 taught by Professor Mwhulver during the Spring '10 term at Virginia Tech.

Page1 / 29

05 Digestive System - The Digestive System HNFE 3025 Fall...

This preview shows document pages 1 - 10. Sign up to view the full document.

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