Released by G-cells in the antral portion of stomach in response to vagal stimulation, peptides in the stomach, and stretch of the stomach. Primarily stimulates HCl secretion and growth of mucosa in the stomach and pancreas. Secondarily stimulates gastric motility and closure of sphincters. B. Secretin 1. secreted by duodenal S-cells in response to decreased acidity nand increased fat 2. Actions a. stimulates pancreatic secretion of enzymes and gall bladder contraction.
Primary action is to promote insulin release.
In general, GI hormones can be delineated into two families. CCK and the gastrins comprise one family. The second family is related to secretin. The homologous regions for these peptides reside internally. Since the peptides in each family are similar, the members of a given group all interact with common receptors though with differing affinity.