Heme Breakdown And Bilirubin Excretion Explained

Heme Breakdown And Bilirubin Excretion Explained

Question 1. Degradation of heme
Answer:

• Heme is split into iron & pigment biliverdin
• Iron goes to the iron pool & is reused
• Biliverdin is reduced to bilirubin by biliverdin reductase
• Bilirubin is released into the blood
• It is taken up by liver cells & gets conjugated
• This conjugated bilirubin is then excreted into the intestine

1. 50% of bilirubin is converted to urobilinogen

• • Most of it enters the liver & re-excreted in bile
  • 5% of it is excreted by the kidney
  • Some of it is excreted in feces as stercobilinogen
  • 50% of bilirubin is absorbed into the blood & enters the liver through the portal vein

Question 2. The fate of bilirubin in the body
Answer:

• Bilirubin is released into the blood
• It is taken up by liver cells & gets conjugated
• This conjugated bilirubin is then excreted into the intestine

1. 50% of bilirubin is converted to urobilinogen

• Most of it enters the liver & re-excreted in bile
• 5% of it is excreted by the kidney
• Some of it is excreted in feces as stercobilinogen

2. 50% of bilirubin is absorbed into blood & enters the liver through the portal vein