Biliary Tract Physiology

Question 1

Where and how is bile formed?

Answer 1

Occurs in the liver in the hepatocytes.

It is formed from a combination of bile acids, cholesterol, water, conjugated bilirubin and phospholipids

Question 2

What is the journey of bile once it has been produced in the hepatocytes?

Answer 2

Bile enters into bile canaliculi between hepatocytes
Canaliculi form thin bile ducts which eventual enter portal tracts and form right and left hepatic ducts (one per lobe of liver)
Joint to form common hepatic duct
Cystic duct joins common hepatic duct at lower end= forms the common bile duct
Common bile duct passes through pancreas
Opens into 2nd part of duodenum with pancreatic duct via ampulla of Vater (AoV)
Sphincter of Oddi in AoV prevents all bile from entering duodenum due to maintaining high pressure

Question 3

Which form of bilirubin is found in bile and how does it differ from the other form?

Answer 3

Conjugated= formed in the hepatocytes

Conjugate= water soluble so it actively excreted into small intestine in bile= then excreted through urine (urobilinogen) or stool (stercobilinogen)

Question 4

What is the compositions of bile?

Answer 4

Bile pigments 
Bile salts 
Bile acids 
Cholesterol 
Phospholipids

Question 5

What stimulates the release of bile?

Answer 5

Cholescystokinin hormone released when fatty meal ingested to stimulate the contraction of the gall bladder to release bile into the duodenum in order to emulsify the fats