1. Gastrin: It is produced by the G-cells of the stomach and helps in the secretion of gastric juice. The hormone gastrin regulates HCl secretion.
2. Somatostatin: This hormone is released from G-cells and hypothalamus and inhibits gastrin secretion. It also reduces gastric secretion and pancreatic juice secretion.
3. Kallikrein: It is secreted from the salivary glands and dilates the blood vessels of the salivary glands. It increases blood circulation. As a result, the amount of salivary secretion also increases.
4. Secretin: Secretin hormone helps in the production of bicarbonate ions in pancreatic and liver cells. Pancreatic juice and bile are more alkaline due to bicarbonate ions. As a result, an alkaline environment is created in the digestive system.
5. Cholecystokinin: It helps in the secretion of bile in the duodenum. In 1928 scientists Ivy and Oldberg discovered the hormone cholecystokinin.
6. Villikinin: Villikinin hormone increases the absorption capacity by strengthening the villi of the small intestine.
7. Testosterone and Estrogen: Testosterone and estrogen regulate protein metabolism.
8. Pancreasin: This hormone helps in the secretion of pancreatic juice. In 1943, Harper and Rapper discovered the hormone pancreozynin.
9. Enterocrinein: This hormone helps in the secretion of intestinal juice. Intestinal juice participates in digestion.
10. Diocranin: It is produced by the wall of duodenum and helps in the secretion of intestinal juice.
11. Peptide YY: Peptide YY is secreted from the wall of the ileum. It makes the food flow slowly. It completes food digestion and absorption.
12. Gastric inhibitory peptide: Gastric inhibitory peptide is secreted from the wall of the duodenum. It controls the passage of food from the stomach into the intestine. It initiates insulin secretion.
13. Vasoactive intestinal peptide: This hormone is secreted from the epithelial wall of the small intestine. It dilates the blood vessels of the intestinal wall. Stops gastric acid secretion.
14. Hormones that regulate hunger and satiety: The hypothalamus of the brain has the hunger center. It regulates human appetite and food intake. Peptide YY, gastric inhibitory peptide (GIP), vasoactive intestinal peptide (VIP), glucagon like peptide-1 (GLP-1), pancreatic polypeptide (PP) and ghrelin act as neurotransmitters in the brain. Among them, peptide YY, pancreatic polypeptide and ghrelin regulate food intake. When the level of ghrelin hormone increases in the blood, hunger is stimulated. When the levels of pancreatic polypeptide and peptide YY hormones increase in the blood during food intake, food satisfaction comes.