Which hormone stimulates the production of gastric acid in the stomach?

Gastrin is the hormone responsible for stimulating the production of gastric acid in the stomach. It is secreted by G cells in the gastric mucosa in response to food intake, particularly proteins. When gastrin is released, it promotes the secretion of hydrogen ions by the parietal cells of the gastric epithelium, leading to an increase in gastric acidity. This acidic environment is essential for the proper digestion of food and activation of digestive enzymes, such as pepsinogen to pepsin.

In contrast, secretin primarily regulates the pH of the small intestine by prompting the pancreas to release bicarbonate, which neutralizes gastric acid. Cholecystokinin (CCK) focuses on stimulating the release of digestive enzymes from the pancreas and bile from the gallbladder, rather than affecting gastric acid production. Insulin plays a significant role in glucose metabolism and does not influence gastric acid secretion directly. Thus, gastrin is the key hormone involved in the stimulation of gastric acid production.