Liver – Bile

Master answer

RBC Destruction

• Globin chains → AA’s 
• Haem → Biliverdin, Fe²⁺, CO

• Biliverdin
  • Haeme + Haem oxygenase → biliverdin
  • Biliverdin + biliverdin reductase → bilirubin
  • Free bilirubin + albumin → transported to hepatocytes
  • Conjugated with glucuronide to ↑ water solubility
  • Excreted to bile canniliculus
  • Secreted to gut at D2 (duodenum)
  • Intestinal flora hydrolyse and reduce → urobilinogen
  • 3 fates:
    1. Gut bacteria form the dark pigment stercobilin, which is egested in the faeces
    2. Urobilinogen reabsorbed unchanged by the portal system and recycled by the liver
    3. Remainder is reabsorbed by the portal system and then excreted in the urine
• Fe2+ → oxidised to Fe3+ → recycled
• CO (only endogenous source of CO)

Hepatic Disease:

• Intrahepatic disease
  • ↓’d conj billi secretion
    • ↑d plasma conjugated bilirubin
    • ↑ urobilinogen in stool
    • ↑ urine bilirubin,
• Posthepatic disease (complete obstruction)
  • ↑ conjugated bilirubin
  • No urobilinogen in stool
  • ↑ urine bilirubin

Gladwin 2016

Answer by Gladwin