Mainly cholecystokinin is secreted by:
Release of cholecystokinin (CCK) from the duodenum and proximal jejunum is triggered by long-chain fatty acids, ceain essential amino acids (tryptophan, phenylalanine, valine, methionine), and gastric acid itself. CCK evokes an enzyme-rich secretion from acinar cells in the pancreas.
Duodenum
Pancreas
Gallbladder
Ileum
Misc.