Physiology of gallbladder

Bile is secreted through a physiological mechanism in the liver that involves several stages as follows

  • Initial secretion by hepatocytes which contains bile acids, cholesterol and other substances. Bile is secreted into bile canaliculi in the liver. From the canaliculi, bile enters terminal bile ducts from small to large ducts from where it enters the hepatic ducts and then to either cystic duct or common bile duct to the duodenum.
  • Watery secretion containing large amounts of sodium and bicarbonate ions is then added to the initial secretion  and it is stimulated primarily by the hormone secretin.
  • Gall bladder holds about 30-60 ml of bile  but it concentrates bile by absorbing water and and small electrolytes in order to concentrate bile by 5 to 2 fold concentration.
  • Gall bladder empties itself by stimuli from fat in the duodenum, and by the hormone cholecystokinin. It is emptied by rhythmic contractions of its walls and the relaxation of the sphincter of Oddi. Finally cholenergic nerve fibers from the vagus and the intestinal enteric nervous system stimulate motility and emptying of the gall bladder but less pronounced than the effect of cholecystokin.

 

Bile is secreted through the cystic duct and gall bladder or directly into the duodenum through the common bile duct. Hence part of the test of liver function includes the production of bilirubin.


Drainage of bile to duodenum through ampulla of Vater and sphincter of Oddi

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


    

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Liver lobule. Click to restart

 
Sphincter of Oddi controlling opening of pancreatic duct and common bile duct into the duodenum
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