QS Study

Bile formation

Bile is a secretory product of liver made up of salt, pigment and other substances, dissolved in an alkaline solution which is stored in Gallbladder. Bile is made up of bile salts, bile pigments and other substances dissolved in an alkaline electrolyte solution. It is a sticky fluid produced in the liver, stored in the gallbladder and delivered into the intestine, where it aids in the digestion of fat.

Bile is secreted in two stages by the liver:

(1) The initial portion containing large amounts of bile acids, cholesterol, and other organic constituents is secreted by hepatocytes into bile canaliculi. This portion then flows into common bile duct (CBD). From this bile either enter directly into the duodenum (when food is taken) or is diverted into the gallbladder (when teed is not ingested, the sphincter is dosed). Once released, it stimulates contractions of the gallbladder and common bile duct, resulting in delivery of bile into the gut.

(2) In its course through the bile ducts, the second portion of secretion containing Na and HCO3 is added to the initial bile. This portion increases the total quantity of bile by as much as an additional 100%. This secretion is stimulated by secretin.  This hormone is secreted in response to acid in the duodenum.

Fig: Liver Secretion and gallbladder emptying

The biliary pathway from hepatocytes to duodenum –

  1. Hepatocyte
  2. Bile canaliculi
  3. Infra lobular bile ductule
  4. Interlobular hepatic ductule
  5. Rt and Lt hepatic duct
  6. Common hepatic duct
  7. Cystic duct
  8. Gallbladder (reservoir)
  9. Common Bile duct
  10. Hepatopancreatic ampulla
  11. 2nd part of the duodenum.
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