Bilirubin metabolism

• what is the order:

  • spleen macrophage
  • blood stream (rbc)
  • liver
  • intestines
  • kidneys
• what Happens in the spleen macrophages

  heme breaks releases Fe and CO

  enzyme: heme oxygenase

  biliverdin is made

  enzyme biliverdin reductase

  Makes unconjugated bilirubin

  secreted to blood stream
• What happens in the blood stream

  Unconjugated bilirubin binds to albumin
• in The liver

  Unconjugated bilirubin uses glucuronyl-bilirubin transferase

  Makes conjugated bilirubin

  goes down gallbladder
• In the intestines


  Conjugated bilirubin changes to urobilinogen

  two pathways: stay in intestines and become stercobilin or travel to blood
• in the kidneys


  Urobilinogen changes urobilin (yellow)
• What happens after the kidneys

  Secreted into urine
• Urobilin 


  Gives urine the yellow coloring
• Stercobilin


  Secretes the stool to give orange/brown color