It acts by binding to secretin receptors located on the pancreas and biliary tract cells. This binding leads to an increase in the intracellular level of cAMP, which in turn activates protein kinase A. The activation of protein kinase A leads to the stimulation of bicarbonate and water secretion.
It includes stimulating the pancreas to release bicarbonate, which neutralizes the acidity of chyme and creates the optimal environment for enzymatic digestion. Secretin also stimulates the liver to release bile and the gallbladder to contract, which helps to emulsify fats in the small intestine. Additionally, secretin helps to stimulate the pancreas to release enzymes that help to digest proteins, carbohydrates, and fats.