CAS BI 315 Lecture Notes - Lecture 9: Bile Acid, Peristalsis, Duodenum
9 Jan 2017
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Document Summary
Basic principles: reflexes initiated by: o distension of the wall by the volume of the luminal contents o chyme osmolarity (total solute concentration) o chyme acidity o chyme concentrations of specific digestion products. Hormonal regulation: cholecystokinin (cck) o hormones produced by the small intestine o stimulated when chyme comes into the small intestine o fat is the best stimulator of cck release. Release of bile timed with ingestion of fat. Gallbladder contraction delivers bile salts to intestine for micelle formation o chyme activates cck release, which relaxes the sphincter of oddi. Releases enzymes and bicarb: most of the bicarb is under the control of secretin, secretin mostly activates bicarb and helps out with enzymes. Presence of fatty acids/ amino acids in the small intestine triggers cck release. As fatty acids/amino acids are absorbed, their concentrations decrease, cck stops: secretin o stimulates pancreatic hco3- secretion o works with cck for a stronger secretion, gastron, glucose-independent insulinotropic peptide (gip)
