What is the primary target organ of the hormone secretin?

Secretin is a hormone produced by the S cells of the duodenum in response to acidic chyme entering from the stomach. Its primary role is to regulate the pH of the intestinal lumen by stimulating the pancreas to secrete bicarbonate-rich fluid. This bicarbonate neutralizes gastric acid, creating a more alkaline environment that is favorable for the action of digestive enzymes in the small intestine.

While secretin also has effects on other organs, such as stimulating the liver to produce bile and influencing the gallbladder, its main and most direct effect is on the pancreas, making it the primary target organ. This function is critical for proper digestion and absorption of nutrients in the small intestine.