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The Exocrine Functions Of The Pancreas

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The Exocrine Functions Of The Pancreas

  1. 1. Chapter 18 The Exocrine Pancreas
  2. 2. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pancreas  Exocrine:  Acini:  Secrete pancreatic juice.  Endocrine:  Islets of Langerhans:  Secrete insulin and glucagon. Insert fig. 18.26
  3. 3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Contains H20, HC03 - and digestive enzymes. Pancreatic Juice
  4. 4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Pancreatic juice is alkaline with high HCO3 content about 113 meq/L  cations: Na, K, Ca, Mg (PH=8.0)  Anions: HCO3,Cl,SO4,HPO4  Digestive enzymes (95% of protein in juice)
  5. 5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  1500 ml of pancreatic juice /day  Pancreatic juice together with bile and intestinal juice neutralize gastric acid raising duodenal PH to (6.0-7.0)
  6. 6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ELECTROLYTES  Produced by centroacinar and duct cells  Mainly in form of NaHCO3  Conc. Of Na and K similar to blood  Conc. Of HCO3 and Cl change according to rate of flow of secretion  Duct cells reabsorb HCO3 in exchange for Cl.
  7. 7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Pancreas contain carbonic anhydrase enzyme for formation of HCO3  Acetazolamide (diomox) is a strong inhibitor of carbonic anhydrase and used for inhibition of pancreatic HCO3 secretion
  8. 8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pancreatic Juice  Complete digestion of food requires action of both pancreatic and brush border enzymes.  Most pancreatic enzymes are produced as zymogens.  Trypsin (when activated by enterokinase) triggers the activation of other pancreatic enzymes.  Pancreatic trypsin inhibitor attaches to trypsin.  Inhibits its activity in the pancreas. Fig. 18.29
  9. 9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. REGULATION OF PANCREATIC SECRETION  Mainly under hormonal control  Secretin: acts on duct cells and centroacinar cells to cause secretion of alkaline juice rich in HCO3 and poor in enzymes
  10. 10. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  CCK: acts on acinar cells to cause release of zymogen granules (enzymes)  Parasym. : Vagi cause secretion of small amounts of pancreatic juice rich in enzymes  There is vagally mediated conditioned reflex secretion of pancreatic juice in response to sight or smell of food.

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