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14 Cards in this Set
- Front
- Back
What are the 2 main components of pancreatic secretions?
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1. aqueous component high in HCO3 (to neutralize H in duodenum)
2. enzymatic component (to digest carbs, lipids, proteins into absorbable molecules) |
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How does the ionic composition of pancreatic secretion compare to that of plasma?
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same Na/K, much higher HCO3, much lower Cl, and is isotonic
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How is the composition of (the aqueous component of) pancreatic secretion affected by low flow rates?
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@ low (basal) rates: s/c's an isotonic fluid that is mainly Na and Cl (when panc is unstimulated)
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How is the composition of (the aqueous component of) pancreatic secretion affected by high flow rates?
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when stimulated by secretin: panc s/c's an isotonic soln that is mainly Na and HCO3 (has been modified by ductal cells)
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What are the transporters/channels present on the apical and basal sides of pancreatic ductal cells?
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apical: Cl-HCO3 exchanger, paracellular Na diffusion = HCO3 s/c, Cl r/a
basal: NaK ATPase, NaH exchanger = H r/a |
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What is the enzymatic component of pancreatic secretion composed of?
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pancreatic amylase and lipases (s/c'ed as active enzymes), inactive panc proteases
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What is the major stimulant of the aqueous HCO3-rich secretion?
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secretin, via cAMP
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Under what conditions and by what cells is secretin secreted?
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is secreted by duodenal S cells in response to H in duod (acidic chyme)
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What is the function of the aqueous HCO3 rich pancreatic secretion?
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to neutralize acidic chyme in duodenum so that pancreatic enzymes lipases wont be inactivated
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What are the 2 main stimulants for enzymatic secretion by pancreatic acinar cells?
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mainly CCK, via IP3/Ca, with potentiation from ACh
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Under what conditions is CCK secreted, and by what cells?
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secreted by duodenal I cells in response to small peptides, AAs, and fatty acids in duod
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What 2 factors potentiate the stimulatory effects of secretin on pancreatic ductal cells?
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CCK and ACh
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What is the molecular defect in cystic fibrosis?
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defect in Cl channels caused by mutation in CFTR gene (cystic fibrosis transmembrane conductance regulator)
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How does the CFTR defect affect pancreatic function?
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causes deficiency of all pancreatic enzymes, resulting in malabsorption and steatorrhea (protein cannot be absorbed if not digested by proteases)
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