Gallbladder contractions are induced by the action of cholecystokinin (CCK), a peptide hormone released by the neuroendocrine cells of the small intestine. The enteroendocrine cells secrete gastrin, which in turn promotes stomach churning and induces more release of gastric juices. Secretin and cholecystokinin are secreted by endocrine cells of the duodenal wall in response to presence of hydrochloric acid in chyme and that of fatty food respectively. Secretin induces the release of pancreatic juice from pancreas, while cholecystokinin induces contraction of gall bladder to release stored bile. Enterogastrone refers to any hormone secreted by duodenum in response to presence of fatty food.