12. Contents of bile, how it's produced & secreted. How jaundice may arise.

Question 1

What are the contents of bile?

Answer 1

Water
Bile acids
Bile salts
Bilirubin
Fats (cholesterol, fatty acids)
Glucuronides

Question 2

How is bilirubin produced and secreted? (Brief)

Answer 2

From the breakdown of haemoglobin by reticuloendothelial cells
Forms unconjugated bilirubin with the haem groups (bound to albumin)
Enters the liver and is conjugated by UDP-glucuronyl transferase
Enters bile duct via canaliculi —–> small intestine
Converted into stercobilinogen and enters large intestine
Some reabsorbed into portal vein for recycling, some reabsorbed into portal vein to be unconjugated and excreted as urobilinogen by the kidneys(?)

Question 3

What are the 3 types of jaundice?

Answer 3

Pre-hepatic - more bile than liver can handle
Hepatic - diseased liver
Post-hepatic - obstruction of bile duct

Question 4

What causes pre-hepatic jaundice?

Answer 4

Haemolytic anaemia - bone marrow activity cannot compensate for the increased loss in RBCs
Resorption of haematoma
Lead to elevated levels of unconjugated bilirubin
Drug induced e.g. methyldopa

Question 5

What causes hepatic (hepatocellular) jaundice?

Answer 5

Viral - hepatitis, EBV etc)
Alcohol
Autoimmune e.g. primary biliary cirrhosis
Drugs

Question 6

What causes post-hepatic (obstructive) jaundice?

Answer 6

Cirrhosis
Tumour or metastases
Gallstones