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Chapter 17 – Part 2

Chapter 17 – Part 2. The Stomach. Digestion Summary. Stomach muscles contract and relax to mechanically break down the food It also mixes the food with gastric juice and hydrochloric acid The acid kills germs in the food and creates optimal pH for enzymes.

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Chapter 17 – Part 2

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  1. Chapter 17 – Part 2 The Stomach

  2. Digestion Summary

  3. Stomach muscles contract and relax to mechanically break down the food • It also mixes the food with gastric juice and hydrochloric acid • The acid kills germs in the food and creates optimal pH for enzymes. • The gastric juice contains the protease enzyme PEPSIN to digest protein into amino acids. • Food spends about 3-4 hours in here.

  4. some water • certain salts • certain lipid-soluble drugs • alcohol Gastric Absorption

  5. Stomach Muscles: Longitudinal, Circular, Oblique

  6. Mixing and Emptying Actions

  7. Why does your stomach growl???

  8. Radiograph of Stomach

  9. Gastric Glands secrete gastric juices/acid (parietal cells) • PEPSIN  - most important digestive enzyme for breaking down food (chief cells) • Mucus prevents stomach from digesting itself Stomach Lining

  10. Lining

  11. Chyme - paste, after food has been broken down, released then into the duodenum via the pyloric sphincter valve

  12. Enzymes and pH • Enzymes work best at one pH. This pH is different for each different enzyme. • If the pH goes too low (more acidic) or too high (more alkaline), the enzyme will not work as effectively.

  13. mucus • from goblet cells and mucous glands • protective to stomach wall • pepsinogen • from chief cells • inactive form of pepsin • hydrochloric acid • from parietal cells • needed to convert pepsinogen to pepsin Gastric Secretions • intrinsic factor • from parietal cells • required for vitamin B12 absorption • pepsin • from pepsinogen in presence of HCl • protein splitting enzyme

  14. Cephalic phase • triggered by smell, taste, sight, or thought of food • nerve impulses trigger gastric juice secretion • Gastrin: • Peptide hormone • Increases secretory activity of gastric glands • Promote mucus production • Stimulates cell growth in mucosa • Gastric phase • triggered by presence of food in stomach • gastrin released • gastric juice secreted and mixes with food Phases of Gastric Secretions • Intestinal phase • triggered by movement of food into small intestine • intestinal cells release intestinal gastrin • secretion of more stomach gastric juice promoted

  15. Both neurally and hormonally controlled. Regulation of Gastric Secretions

  16. Regulates the rate at which chyme leaves the stomach Enterogastric Reflex

  17. Stress and diet play a role in severity but are NOT the cause. • The bacterium associated with stomach ulcers is quite common. • About ½ of all people in the U.S. under the age of 60 is likely to have helicobacter pylori. Stomach Ulcers

  18. Inability to digest milk, can cause stomach upset Lactose Intolerance

  19. http://www.hurtbyadoctor.com/Gastric-Bypass-Surgery-Malpractice-Lawsuits-Information-Home.htmhttp://www.hurtbyadoctor.com/Gastric-Bypass-Surgery-Malpractice-Lawsuits-Information-Home.htm Gastric Bypass Surgery

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