Which hormone is triggered by acidic chyme in the duodenum?

The hormone that is triggered by acidic chyme in the duodenum is secretin. When the acidic contents from the stomach, known as chyme, enter the duodenum, they stimulate the cells in the intestinal lining to secrete secretin. This hormone plays a critical role in regulating the pH of the intestinal environment by promoting the release of bicarbonate from the pancreas. Bicarbonate neutralizes the acidity of the chyme, creating a more favorable pH for the action of digestive enzymes in the small intestine.

Furthermore, secretin also stimulates the liver to produce bile, which is important for the emulsification of fats, and helps to regulate overall digestive processes in the small intestine. This response ensures that the digestive system functions efficiently and safely, preventing damage to the intestinal lining from excessive acidity.

The other hormones listed have different roles: gastrin primarily stimulates the secretion of gastric acid in the stomach, cholecystokinin (CCK) is primarily involved in the release of digestive enzymes and bile in response to fats and proteins, and insulin regulates blood sugar levels. Therefore, secretin is specifically linked to the presence of acidic chyme and is essential for maintaining homeostasis in the digestive system.