Cholecystokinin is a very technical term. As the name suggests, cholecystokinin is a substance that causes the gallbladder to contract. After secretion of this hormone by the mucous membrane cells of the small intestine, it innervates the gallbladder through the nerve pathway, causing the gallbladder to contract and the pancreas to secrete pancreatic enzymes. When a person eats a lot of high-fat food, the food enters the small intestine and gives a signal to the small intestine mucosa to secrete cholecystokinin, which is transmitted to the gallbladder to send a command for the gallbladder to contract and excrete the stored bile into the duodenum. In addition, cholecystokinin causes the pancreas to secrete pancreatic enzymes, which are excreted into the duodenum. When bile and pancreatic enzymes work together some chemical changes occur that facilitate the digestion and absorption of high oil and fat things with great efficiency.