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14 Cards in this Set

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