Exocrine Functions of Pancreas S2M2

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Exocrine Functions of Pancreas S2M2
2011-08-13 17:47:07
Ross S2M2

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  1. What makes the pancreas the main digestive organ
    • Secretion of:
    • Proteases
    • Lipases
    • Amylase
    • HCO3
    • 1.5L of secretions a day
  2. What path do pancreatic secretions follow to arrive in the duodenum
    • Acinus
    • Intralobular ducts
    • Lubular ducts
    • Main duct
    • Common bile duct
    • Duodenum
  3. What are the two stages of Pancreatic secretion
    • Primary
    • - Isotonic
    • - NaCl (Acini)
    • - Enzymes
    • Ductal modification
    • - HCO3 secreted
  4. Secretion of acinar fluid and the proteins that it contains is stimulated by
    • Cholecystokinin (CCK)
    • Acetylcholine
    • Gastrin-releasing peptide
    • (all act by mobilizing intracellular Ca++)

    VIP and Secretin (act on cAMP)
  5. The hormone Secretin stimulates secretion of what in the pancreas
    Water and electrolytes from the cells that line the extralobular ducts
  6. Where are the enzyme containing granules found on the acinar cells
    Apical end
  7. Trypsinogen is activated to Trypsin by
    Enterokinase found on the brush border cells of the intestines and in turn activates the rest of the enzymes released by the pancreas
  8. Enzymes secreted from acinar cells are in what form
  9. I cells are found where and have what function
    They are found on the epithelium of the intestines and they release CCK in to the blood stream
  10. I cells release Cholecystokinin (CCK) into the blood stream when triggered by
    • CCK releasing peptide (paracrine messenger)
    • Monitor peptide (from pancreas)
    • Amino acids
    • Fatty acids
  11. Presence of what inhibits the stimulation of I cells to release CCK into the blood stream
  12. What is the mechanism for keeping the pH of the intestines constant
    • - low pH in Duodenu (below 4.5) causes S cells to release Secretin
    • - Ductular cells (triggered by secretin) in the pancreas release bicarbonate
    • - pH raises and inhibits further release from S cells
  13. In the un-stimulated state, the pancreatic flow is
    • Low, and the electrolyte composition of
    • pancreatic juice closely resembles that of blood plasma
  14. HCO3 release from the pancreas is done by what cells, under what direction
    • Intralobular ducts
    • Secretin & Acetylcholine
  15. What type of channel or pump is used in the Intralobular ducts and main ducts to excrete HCO3 into the lumen
    HCO3/Cl- exchange
  16. The HCO3/Cl- exchange on the intralobular duct cells is dependent on
    Secretion of CFTR protein and availability of Cl- in the lumen
  17. How does bicarbonate get into the interlobular cells of the pancreas
    • Through a cotransport of Sodium and Bicarbonate on the basal end of the cell
    • It is also made inside the cell via carbonic anhydrase
  18. How does carbon dioxide and water enter the cell for bicarbonate synthesis (carbonic anhydrase)
    Passive diffusion across the membrane, no pump or channel are necessary
  19. What are the three phases of enzyme and bicarbonate secretion from the pancreas
    • Cephalic
    • Gastric
    • Intestinal
  20. What triggers the cephalic phase in pancreatic secretion
    • Sight, smell, and taste triggers the Vagus
    • Vagus causes release enzymes directly
    • Vagus causes indirect enzyme secretion through stimulation of gastrin releasing peptide which causes releases in gastrin, causing enzyme release
  21. How is the Gastric phase of pancreatic secretion triggered
    • Distension of intestines
    • Vago-vagal reflex
    • Enzyme release
  22. In what three ways is the intestinal phase of pancreatic secretion triggered
    • 1. H+ and fats trigger Secretin
    • Secretin causes the release of Bicarbonate
    • 2. Amino acids and fats cause CCK release
    • CCK induces enzyme secretion
    • 3. Vago-vagal response (distension of intestines)
  23. What is the comparative influence of pancreatic secretion between the 3 different stages
    • Cephalic - 25%
    • Gastric - 10-20%
    • Intestinal - 50-80%
  24. What signals are most influential in increasing Secretin
    • ACh
    • CCK