( 1 ) the contractile effects are due to excitement of cholinergic neurons in the myenteric plexus of the biliary tract , ( 2 ) the direct action of neurotensin on the smooth muscle of the bile duct and ampulla results in a small contraction , ( 3 ) the contraction in the gallbladder is partly caused by stimulation of prostaglandin synthesis .
C0005423
biliary tract
C0005400
bile duct