Lecture 30 – Digestion II

Lecture 30 – Digestion II - Lecture 30...

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Lecture 30 – Digestion II A. Stomach 1. Four basic areas 1) Cardia (fig. 46.8) – directly in contact with the esophageal sphincter 2) Fundus – dome-shaped portion, in contact with the diaphragm; fundus can be wrapped around esophagus to help control acid reflux by acting as another muscle 3) Body – the large, central area of the stomach 4) Pylorus – funnel-shaped terminal portion, ends at the pyloric sphincter (there is a sphincter muscle at both ends of the stomach to keep food in there while its being churned) 2. Rugae (fig. 46-9) - folds inside of the stomach - if the stomach is empty it has a capacity of 1 L, but the rugae allow it to expand to 4 L 3. Stomach content a) Gastric juices – made of lots of water (to moisten and separate the bolus), hydrochloric acid (pH 1-3) b) Pepsin – starts to break down proteins; active at pH 2 c) HCl – amylase breaks food down in the mouth, when the amylase moves to the stomach it is deactivated by the HCl pH d) Gastrin – hormone; when food is in the lower part of the stomach gastrin is stimulated (the receptor site, target site, are the cells of upper part of the stomach and the cells in the lower part secrete it); tells the cells of the upper stomach to produce pepsin (produced in an inactive form called pepsinogen, which is converted to pepsin by HCl) and HCl - Why is pepsin in an inactive form? To prevent it from digesting your own proteins e) Acid chyme – the food is mushed into a thick soup that will leave the stomach f) Helicobacter pylori – a bacteria that can enter your stomach, through the feces-oral route
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This note was uploaded on 05/30/2008 for the course BS 131 taught by Professor Smith during the Spring '08 term at University of the Sciences in Philadelphia.

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Lecture 30 – Digestion II - Lecture 30...

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