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13 Cards in this Set
- Front
- Back
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Outline the innervation of the pancreas and describe the interaction between the extrinsic nerves and intrinsic ganglia:
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Parasympathetic - vagus nerve
Sympathetic - celic and superior mesenteric ganglia Extrinsic nerves communicate with small intrinsic ganglia throughout the pancreas which innervate blood vessels, acini, duct cells, and islet cells. |
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What are the intrinsic neurotransmitters of the Pancreas?
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Ach
VIP |
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Describe what happens to acinar and duct cell secretions in response to a meal:
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Pre-prandial: secretion (~2% of maximum) of Na+ and Cl- from acinar cells
Post-prandial: secretion (large volumes) of Na+ and HCO3- from duct cells |
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How does Cystic Fibrosis interfere with HCO3- production?
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The cystic fibrosis transmembrane conductance regulator effluxes Cl- into the lumen, its dysfunction interferes with Cl-/HCO3- exchangers which are dependent on luminal chloride. In CF altered Cl- secretion into the lumen results in decreased HCO3- production.
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What is the stimulus for the up regulation of the cystic fibrosis transmembrane conductance regulator:
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Vasoactive intestinal peptide (VIP)
Secretin |
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Where are pancreatic enzymes synthesized?
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Acinar Cells
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List the major pancreatic enzyme classes and the enzymes they include:
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Amylolytic: α-Amylase
Lipolytic: Lipase, Procolipase, Prophopholipase A2, Cholesterolesterase Proteolytic (Proteases): Trypsinogen, Chymotrypsinogen, Proelastase, Procarboxypeptidases A & B Nucleases: Ribonuclease, Deoxyribonuclease |
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What mechanism employed by ascinar cells to avoid auto-digestion by the exocrine enzymes is secretes?
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Enzymes are co-packaged with trypsinogen and trypsin inhibitor into zymogen granules. Activation occurs in the duodenum where the brush border enzyme enterokinase converts trypsinogen into trypsin which autocatalyzes more trypsin and activates the other zymogens.
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Briefly describe the three phases of pancreatic exocrine secretion:
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Cephalic - taste, thought, sight, and smell of food induce a small secretion
Gastric - gastric distension induces a further secretion. Intestinal - acidic chyme entering the duodenum stimulates full secretion |
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Outline the innervation of the cephalic phase of pancreatic exocrine secretion:
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Vagal cholinergic fibers activate intrinsic cholinergic neurons to prime the duct lumen enzymes, H2and HCO3- .
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Outline the innervation of the gastric phase of pancreatic exocrine secretion:
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Gastric stretch receptors sense food bolus in stomach and activate enzyme secretion via vago-vagal reflex and gastropancreatic nerves.
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Outline the innervation of the intestinal phase of pancreatic exocrine secretion:
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Acidic chyme entering the duodenum triggers a vago-vagal reflex to stimulate secretion; also, pH<4.5 triggers duodenal release of secretin to act on the pancreatic ducts to secrete HCO3- and H2O to mildly stimulate acinar cell enzyme secretion. Cholecystokinin (CCK) is released from the duodenum, it acts directly on acinar cells to stimulate enzyme secretion, and interacts with secretin to stimulate acid secretion, gallbladder contraction and relaxes the sphincter of oddi located at the major duodenal papilla. A vaso-vagal reflex also occurs resulting in a neutrally-mediated acinar cell secretion.
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What is the role of pancreatic HCO3- secretions?
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HCO3- is necessary to neutralize the acidic chyme entering the duodenum.
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