What stimulates the release of secretin?

The release of secretin is primarily stimulated by the presence of acid in the duodenum. When gastric acid enters the duodenum from the stomach, it is detected by the S cells found in the lining of the duodenum. In response to this acidic environment, these cells release secretin into the bloodstream.

Secretin plays a crucial role in maintaining the pH balance in the digestive system. It stimulates the pancreas to secrete bicarbonate-rich fluid, which neutralizes the acid, allowing digestive enzymes to function effectively in the more alkaline environment of the small intestine. Additionally, secretin also inhibits gastric acid secretion and promotes bile secretion from the liver, further aiding in digestion and absorption.

The other factors listed, such as fats and amino acids, can stimulate other hormones but are not primary triggers for secretin. Fats primarily stimulate cholecystokinin (CCK) release, while amino acids can influence other hormonal responses but do not directly affect secretin secretion. Increased gastric acidity is addressed by secretin, but it is the acidity in the duodenum itself that serves as the direct stimulus for its release.