Hormones Secreted by the Stomach

Enteroendocrine cells are specialized cells scattered throughout the gastric glands that secrete digestive hormones. Though they account for only 1% of stomach epithelial cells, they play a significant role in digestion. These cells are typically located at the base of gastric glands among mucus-secreting cells in the fundic region.

Gastrin, secreted by G cells, stimulates gastric acid production and enzyme release from parietal cells. It enhances stomach muscle contractions to facilitate food movement through the digestive tract. Gastrin essentially initiates and maintains the stomach's digestive activity during the gastric phase of digestion.

Somatostatin, released by D cells, inhibits gastrin secretion and slows digestion when stomach acidity becomes excessive. This hormone acts as a regulatory brake, preventing overproduction of gastric acid and ensuring a balanced digestive process. It also regulates the secretion of other digestive hormones.

Ghrelin, produced by P/D1 cells, is known as the hunger hormone because it stimulates appetite and promotes growth hormone release. Ghrelin levels spike before meals to initiate hunger and decrease shortly after eating, curbing appetite. It plays an essential role in regulating metabolism and energy balance.

Histamine, produced by enterochromaffin-like cells, stimulates gastric acid release from parietal cells in the stomach lining. This hormone works alongside gastrin to enhance acid production necessary for protein digestion. Histamine is a key chemical messenger in the stomach's digestive response.

Serotonin, secreted by enterochromaffin cells in the stomach mucosa, regulates gastrointestinal motility to ensure smooth food movement through the digestive tract. By controlling muscle contractions, serotonin facilitates the progression of food from the stomach into the small intestine for mechanical and chemical digestion.

Stomach hormones coordinate through complementary and opposing actions: gastrin and histamine stimulate acid production, while somatostatin inhibits excessive secretion. Ghrelin regulates appetite timing, and serotonin controls food movement. Together, these hormones ensure proper digestion and absorption of nutrients while maintaining digestive system balance.