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Stomach Anatomy and Activity Control of Digestion SI Anatomy Macromolecule Digestion Absorption Handout: Reflexes in the Stomach (in class) Marieb: 23 The SI is the Main Digestive Organ 1” in diameter 6-7m in cadaver 2-4m in living person Chemical Digestion Absorption Small Intestine: Gross Anatomy Pyloric sphincter Duodenum*** Jejunum Illeum Ileocecal Valve Small Intestine is Specialized for Absorption Mucosa has a huge surface area Plicae circulars (1cm) Villi in the Small Intestine Villus (1mm) Capillary bed Lacteal Intestinal Crypts Microvilli in the Small Intestine Brush Border 1/1000 of mm Enzymes Final protein and carbohydrate digestion Cells of the Villi Enterocytes Goblet cells Enteroendocrine cells Secretin CCK Cells of the Crypt Stem Cells Cells replaced every 3-6 days Enzyme Production??? Accessory Glands aide SI Digestion Digestion in SI: 3-6 hours Liver Gall Bladder Pancreas Pancreas and Liver aid in Digestion Pancreas Aids in Digestion Pancreatic juice: 12001500ml/day (pH ~8.5) Pancreatic Enzymes Pancreatic Enzymes Amylases Zymogens Inactive in the pancreas Activated in the small intestine SI Digestion and Absorption Pancreatic Enzymes Brush Border Transport into cell Transport into capillary bed of villi The Liver is a Versatile Organ Detoxification Activates Hormones and Vitamins Stores Nutrients Produces Bile The Liver makes Bile Salts Cholesterol Derivatives Emulsifies Fat Placed in Bile: 500-1000ml/day Gall Bladder stores bile CCK Triggers Bile Release Low pH Fat Proteins Cholecystokinin (CCK) Gall bladder contracts Absorption of Fats Bile Salts + Fats= Micelles Chylomicrons Absorption of Fats Lacteals Chyle Fats broken down in blood or liver Secretin and CCK Regulate the Pancreas Secretin HCl activates release Pancreatic juice CCK Fat activation Enzymes Absorption in the SI 10-12L 1200ml 99% Nutrients 80% electrolytes and H2O Small Intestine Motility: Segmentation Segmentation Duodenum 12-14/min Ileum 8-9/min Small Intestine Motility: Peristalsis Migratory Mobility Model Process repeats itself twice
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