a digestive hormone released with secretin when food from the stomach reaches the first part of the small intestine (the duodenum). Once considered to be two separate hormones because of its two distinct actions, cholecystokinin/pancreozymin evokes the release (ascribed to pancreozymin) of enzymes from the pancreas; it also causes contraction (ascribed to cholecystokinin) of the gallbladder, thereby forcing bile into the duodenum.