Cholecystokinin (CCK) is a hormone produced in the small intestine that plays a key role in digestion. When we eat, especially foods high in fats and proteins, CCK is released into the bloodstream. This hormone helps stimulate the gallbladder to release bile, which aids in breaking down fats, and it also signals the pancreas to produce digestive enzymes. In addition to its digestive functions, CCK helps regulate appetite. It sends signals to the brain to promote feelings of fullness after eating, which can help control food intake. Overall, CCK is essential for both digestion and maintaining a healthy appetite.