What is CCK's primary function in the digestive system?

Cholecystokinin (CCK) is a peptide hormone primarily involved in the digestive system, and one of its key functions is to stimulate gallbladder contraction. When food, especially fats and proteins, enters the small intestine, CCK is released from the intestinal cells. This hormone then signals the gallbladder to contract, releasing bile into the intestine, which is essential for the digestion and emulsification of fats.

In addition to stimulating gallbladder contraction, CCK also plays a role in slowing gastric emptying and promoting satiety, but the primary question focuses on its action concerning the gallbladder. The release of bile enhances the ability to digest dietary fats, making this function crucial for effective digestion.

The other options, while they describe processes involved in digestion or metabolism, do not accurately reflect CCK's primary role. For example, CCK does not enhance stomach acid production or promote insulin secretion to any significant extent, and while it does have an effect on appetite inhibition as part of its broader function, its most direct and recognized action is related to gallbladder contraction.