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Digestive System

Digestive System. Accessory Organs. 1. Oral Cavity. Tongue Skeletal muscle Forms a bolus from food and saliva Papillae – projections of mucosa on superior surface Increase surface area Creates friction Contains taste buds. Salivary Glands - produce saliva

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Digestive System

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  1. Digestive System Accessory Organs

  2. 1. Oral Cavity

  3. Tongue • Skeletal muscle • Forms a bolus from food and saliva • Papillae – projections of mucosa on superior surface • Increase surface area • Creates friction • Contains taste buds

  4. Salivary Glands - produce saliva • Cleanses mouth & dissolves food particles for tasting • Moistens food; helps form bolus • Saliva Composition: 97-99% Water • Salivary amylase – enzyme that digests starch • Electrolytes • IgA, Lysozyme – provide immune defense

  5. 2. Liver & Gallbladder

  6. Gross Anatomy • Largest gland in the body • 4 Lobes • Weighs ~ 3 lbs • Falciform Ligament • Ducts • R&L Hepatic • Common Hepatic • Common bile

  7. Microscopic Anatomy • Liver Lobule– basic structural/functional unit; filters toxins from blood and absorbs nutrients

  8. Digestive Functions • Produces bile • Stored by Gallbladder • Transferred to Duodenum

  9. Bile • Emulsifies fats – separating large globules into smaller droplets • Increases S.A. for lipases to work

  10. When fatty chyme arrives in SI from stomach, intestinal glands secrete CCK and secretin • Secretin causes the liver to secrete more bile • CCK stimulates the gallbladder to contract and release bile into the SI

  11. 3. Pancreas

  12. Anatomy • Lies behind the stomach; secretes into duodenum • Gland composed of epithelial tissue

  13. Exocrine Functions Secretes: • Amylase– completes starch digestion • Trypsin, Chymotrypsin- ~1/2 of all protein digestion • Lipases– all fat digestion • Nucleases – digest nucleic acids • Bicarbonate solution – basic pH to neutralize acidic stomach chyme

  14. Control of Pancreatic Secretions • When chyme arrives in SI from stomach, intestinal glands secrete CCK and secretin • Secretin causes the pancreas to secrete bicarbonate-rich buffer fluid • CCK stimulates the pancreas to secrete enzymes

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