It stimulates pancreatic enzyme synthesis and secretion, increases gall bladder emptying and decreases gastric emptying. A chronic effect of CCK is the stimulation of DNA synthesis in the exocrine pancreas and growth of mucosal tissue. Gastrin is a 17 amino acid polypeptide hormone made in the duodenum and pyloric antrum. The presence of digested protein in the stomach and duodenum stimulate its release. Gastrin stimulates acid secretion from the parietal cells of the gastric glands and pepsinogen secretion from the chief cells.
Histamine is a mediator in the gastrin stimulated release of gastric acid.
Gastrin also stimulates nucleic acid and protein synthesis and growth of the exocrine pancreas, mucosa of the small and large intestine and glandular stomach. It also inhibits gastrin release and gastric acid secretion. Absorptive capabilities vary over the length of the intestine with the bulk of substances being absorbed in the ileum. The site of absorption varies with nutrient as does the mechanism. Some nutrients are absorbed passively along their concentration gradient while others are actively absorbed using carriers in an energy requiring process.