Hepatic Bilirubin Transport 1. Hepatic uptake of Bilirubin UCB-Albumin Complex separated (be) taken up Bilirubin MTA(receptor Plasma membrane of the liver 2. Conjugation of Bilirubin ligation (Y protein) carrier transfer UCB (be) bound to ER (lipid soluble) protein Conjugation Z protein (catalized by UDPGT 3. Biliary Excretion of Bilirubin CB CBGA (water soluble) Transfer across CB → Bile canaliculus Microvillar membrane
CB 1. Hepatic uptake of Bilirubin UCB~Albumin Complex Separated Bilirubin Plasma membrane of the liver (be) taken up MTA (receptor ?) Transfer across Microvillar membrane 3.Biliary Excretion of Bilirubin Bile canaliculus 2.Conjugation of Bilirubin UCB carrier protein ER CB CBGA (be) bound to transfer Conjugation (catalized by UDPGT) ligation (Y protein) Hepatic Bilirubin Transport (lipid soluble) (water soluble)
UDPGT: Uridine Diphosphate glucuronyl Transferase UCB: because of its tight albumin binding and lipid solubility, it is not excreted in urine。 CB: is less tightly bound to albumin and is water soluble. so it is filtered at the glomerulus and appears in the urine
• UDPGT: Uridine Diphosphate Glucuronyl Transferase • UCB: because of its tight albumin binding and lipid solubility, it is not excreted in urine. • CB: is less tightly bound to albumin and is water soluble, so it is filtered at the glomerulus and appears in the urine
Entero-hepatic circulation cB-TBandi be degraded Urobilinogen(coloreds) Bacterial Enzymes feces(fecal urobilinogen) 50-200mgd most re-excreted excreted 90%,liver Bile → feces 20% Reabsorbed→→ plasma trace circulation--kidneys 4 mg/d urine urobilinogen . The serum of normal adults contains sI mg of bilirubin per 100 ml .In healthy adults The direct fraction is usually <0.2 mg/100 ml The indirect fraction is usually <0.8 mg/100 ml
Entero-hepatic circulation CB B and I Urobilinogens (coloress) be degraded Bacterial Enzymes feces (feceal urobilinogens) Reabsorbed plasma circulation kidneys 50-200 mg/d mostly 4 mg/d urine urobilinogen T liver Bile feces re-excreted excreted 90% trace 20% •The serum of normal adults contains 1 mg of bilirubin per 100 ml. •In healthy adults The direct fraction is usually <0.2 mg/100 ml The indirect fraction is usually <0.8 mg/100 ml
Pathophysiologic classification of Jaundice a Hemolytic Jaundice a Hepatic Jaundice a Obstructive jaundice
Pathophysiologic classification of Jaundice ◼ Hemolytic Jaundice ◼ Hepatic Jaundice ◼ Obstructive Jaundice
Hemolytic Jaundice Pathogenesis Overproduction s Hemolysis(intra and extra vascular) inherited or genetic disorders x acquired immune hemolytic anemia (Autoimmune hemolytic anemia) x nonimmune hemolytic anemia (paroxysmal nocturna Hemoglobinruia) .s Ineffective erythropoiesis Overproduction may overload the liver with UB
Hemolytic Jaundice Pathogenesis Overproduction ❖ Hemolysis (intra and extra vascular) inherited or genetic disorders acquired immune hemolytic anemia (Autoimmune hemolytic anemia) nonimmune hemolytic anemia (paroxysmal nocturna Hemoglobinruia) ❖ Ineffective erythropoiesis Overproduction may overload the liver with UB