BLD 402: BILIRUBIN EXAM ACTUAL QUESTIONS AND ANSWERS
WITH COMPLETE SOLUTIONS GRADED A++
What role do splenic macrophages play in the trafficking and matabloism of
bilirubin?
-Seperates hemoglobin into heme and globin and converts
-Heme oxygenase converts heme into biliverdin
-Biliverdin reductase converts biliverdin into unconjugated bilirubin
What happens to unconjugated bilirubin once it leaves the spleen and enters the
blood flow?
Unconjugated bilirubin binds to albumin because it is insoluble in water
What is the liver's role in bilirubin trafficking and metabolism?
-Hepatic uptake: unconjugated bilirubin binds to transport protein to cross the hepatic
cell membrane and leaves albumin
-In hepatocytes, unconjugated bilirubin binds to ligandin because it is insoluble in water
-Conjugation: uridine diphosphate (UDP)- glucuronyl transferase adds one or two
glucuronyl group (very polar group ---> conjugated bilirubin (water soluble)
-Conjugated bilirubin is excreted to bile canaliculus ---> becomes component of bile
What is the bile duct/intestine's role in bilirubin trafficking and metabolism?
-Intestinal flora convert conjugated bilirubin to urobilinogens (colorless)
-Enterohepatic circulation: some of the urobilinogens are reabsorbed at ileum (end of
intestine) ---> portal vein ---> either re-excreted to bile or excreted from kidney.
WITH COMPLETE SOLUTIONS GRADED A++
What role do splenic macrophages play in the trafficking and matabloism of
bilirubin?
-Seperates hemoglobin into heme and globin and converts
-Heme oxygenase converts heme into biliverdin
-Biliverdin reductase converts biliverdin into unconjugated bilirubin
What happens to unconjugated bilirubin once it leaves the spleen and enters the
blood flow?
Unconjugated bilirubin binds to albumin because it is insoluble in water
What is the liver's role in bilirubin trafficking and metabolism?
-Hepatic uptake: unconjugated bilirubin binds to transport protein to cross the hepatic
cell membrane and leaves albumin
-In hepatocytes, unconjugated bilirubin binds to ligandin because it is insoluble in water
-Conjugation: uridine diphosphate (UDP)- glucuronyl transferase adds one or two
glucuronyl group (very polar group ---> conjugated bilirubin (water soluble)
-Conjugated bilirubin is excreted to bile canaliculus ---> becomes component of bile
What is the bile duct/intestine's role in bilirubin trafficking and metabolism?
-Intestinal flora convert conjugated bilirubin to urobilinogens (colorless)
-Enterohepatic circulation: some of the urobilinogens are reabsorbed at ileum (end of
intestine) ---> portal vein ---> either re-excreted to bile or excreted from kidney.
