1. Digestion Structure of the wall of the GI tract Sphincters Gastric emptying Vomiting

2. Exocrine glands zHave ducts zEpithelium is continuous w/ body surface zEx: Salivary, gastric glands, pancreas, bile glands in liver, sweat glands http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/ExocrineGlands.html

3. Wall of the GI Tract zMucous Membrane yEpithelium (varies) yLamina propria (Connective tissue) yMuscularis Mucosa (smooth muscle) zSubmucosa

4. Muscularis Externa, Serosa zMuscularis Externa: 2 layers of smooth muscle yInner circular fibers yOuter longitudinal fibers yNeural network in between xEnteric nervous system zSerosa: outermost layer yConnective tissue ySquamous cells

5. Muscularis Externa Layers

6. Sphincters  UES  LES  Pyloric  Ileocecal  Internal anal  External anal

7. GI secretions zGastric: yGastrin:  gastric juice secretion zEnterogastrones: ySecretin:  bicarbonate from pancreas CCK:  bile (contractions from gall bladder) in response to amino, fatty acids  pancreatic enzymes

8. Gastric Emptying zNeeds to be mediated so rate of emptying into the small intestine isn’t greater than rate of small intestine processing zPresence of acid in the duodenom  secretin  closes pyloric sphincter, stimulates secretions of the pancreas zPresence of fat: release of CCK  closes pyloric sphincter zPresence of peptides/amino acids: release of gastrin  closes pyloric sphincter

9. Yaking, spewing, blowing chunks, hurling, etc. (vomiting) zReflex, expulsion of stomach/duodenal contents zRetching: contents forced into esophagus, not up to pharynx zReverse peristalsis zPyloric sphincter relaxes

10. Yaking (continued) z“vomiting center” in medulla signaled by: xDistension of stomach, pressure in the back of the throat xInjury to urogenital area xDizziness zEmetics: stimulate stomach/duodenum receptors to induce vomiting yEx: ipecac