Regulation of Bile Secretion and Release
Secretin released form the duodenum stimulates bile secretion,primarily by increasing the water and bicarbonate ion content of bile (figure 21.21). Cholecystokinin released from the duodenum stimulates the gallbladder to contract and sphincters of the bile duct and hepatopancreatic ampulla to relax. To a lesser degree, parasympathetic stimulation through the vagus nerves causes the gallbladder to contract. Thus, large amounts of concentrated bile move rapidly into the duodenum.