How does cholecystokinin (CCK) affect the Oddi sphincter?

Cholecystokinin (CCK) plays a critical role in the digestive process, particularly in the regulation of bile and pancreatic enzyme secretion. When food, especially fats and proteins, enters the small intestine, CCK is released from the intestinal mucosa. One of its key functions is to promote the relaxation of the sphincter of Oddi, which is a muscular valve that controls the flow of bile and pancreatic juices into the duodenum.

This relaxation allows the bile, which is stored in the gallbladder, and the pancreatic enzymes, produced by the pancreas, to flow freely into the digestive tract where they are needed to aid in the digestion of food. By facilitating this release, CCK enhances the digestive process, ensuring that nutrients are properly broken down and absorbed.

In contrast, the other options do not accurately reflect the action of CCK. For example, CCK does not constrict the Oddi sphincter to store bile; rather, its role is to enable the release of digestive juices. It also does not stimulate gastric acid secretion, as that function is primarily managed by gastrin and other factors. Additionally, CCK's function is not to inhibit bile flow; in fact, it actively promotes the flow of