1. There are scattered endocrine cells in different parts of alimentary canal.
2. These cells secrete four peptide hormones which are gastrin, secretin, cholecystokinin (CCK) and gastric inhibitory peptide (GIP).
3. Gastrin stimulates gastric glands for the secretion of hydrochloric acid and pepsinogen.
4. The secretin acts on exocrine pancreas and stimulates secretion of water and bicarbonate ions to form pancreatic juice.
5. CCK acts on pancreas and gall bladder and stimulates the secretion of pancreatic enzymes and bile juice respectively.
6. GIP inhibit gastric secretion and motility.
