Secretion released from the duodenum stimulates bile secretion,primarily by increasing the water and bicarbonate ion content of bile (figure21.21). Cholecystokinin released from the duodenum stimulates the gallbladder to contract and sphincters of the bile duct and hepatopancreatic Camilla to relax. To a lesser degree, parasympathetic stimulation through the vagus nerves causes the gallbladder to contract. Thus,large amounts of concenttarated bile move rapidly into the duodenum. Bile salts also increase bile secretion through a positive-feedback system. Over 90% of bile salts are absorbed in the Klein and carried in the blood back to the liver,where they contribute to further bile secretion. The loss of bile salts in the feces is reduced by this recycling process.