What effect does CCK have on the gallbladder?

Cholecystokinin (CCK) plays a significant role in digestion by influencing the gallbladder's function. The primary effect of CCK on the gallbladder is to stimulate its contraction. When fatty acids and certain amino acids enter the small intestine, CCK is released into the bloodstream. This hormone then signals the gallbladder to contract, which results in the release of bile into the duodenum.

Bile is essential for the emulsification and absorption of fats in the digestive process, and the contraction of the gallbladder ensures that sufficient bile is available when it is needed. This action is essential for effective fat digestion and absorption. In contrast, other physiological processes are regulated differently; for instance, the relaxation of the gallbladder or inhibition of bile release would not facilitate the digestion of fats, making contraction the correct and essential mechanism by which CCK operates in this context.