The contraction of gall bladder is stimulated by a hormone secreted by the

The contraction of the gallbladder is stimulated by a hormone secreted by the gastrointestinal tract. The hormone involved in this process is cholecystokinin (CCK), which is released in response to the presence of fats and proteins in the duodenum (the first part of the small intestine). CCK signals the gallbladder to contract, releasing bile into the small intestine to aid in the digestion and absorption of fats.