2 - Hepatic Physiology Flashcards
If the liver is too big
It will shrink
If the liver is too small
It will grow
Bilirubin Produced By
Oxidation of Heme and Reduction of resultant bilverdin
Heme oxygenase converts Heme to Biliverdin
Biliverdin Reductase converts Bilverdin into Bilirubin
After C-Glycine Administration Early Peak
Ineffective Erythropoiesis
Conjugation of Bilirubin
To make it more soluble
Bilirubin
Delivered in sinusoid
Uptaken into hepatocyte
Biotransformed and secreted into biliary flow
Glucuronyl Transferase
Does something I don’t know he did not use enough words
Bilirubins
Unconjugated (UCB)
Mono-Glucuronide (BMG)
Diglucuronide (BDG)
These are progressive steps
Bacterial Breakdown of Bilirubin
In color
Gives stool brown color
Deconjugation
Reduction
Oxidation
No bilirubin in stool
Clay colored stool
Biliary Atresia
Agenesis of common bile duct
Treat with “Cuh-sai” procedure
Sew intestine into intrahepatic bile ducts
Stool color doesn’t matter much actually. Stool swatches were more for parents. What more counts is bilirubin in serum.
Enterohepatic Circulation of Bilirubin - In Hepatocyte dysfunction (hepatocellular)
Increased urobilinogen in urine because it is less efficiently reabsorbed by hepatocytes
Enterohepatic Circulation of Bilirubin - In Biliary Obstruction
Stools appear white
No urobilinogen detected in urine
Measurement of bilirubin in blood
=
Hyperbilirubinemia and Jaundice
Occur when liver fails or when other steps of the metabolism are abnormal.
Bilirubin >35μM can begin to detect jaundice clinically.
Coca Cola urine
Beefy Red Liver
Bile getting stuck in liver
Leads to micronodules too
Cause of Unconjugated Hyperbilirubinemia
Overproduction: Hemolysis or Ineffective Erythropoiesis
Impaired Uptake: Fast, Sepsis, Drugs (eg probenecid)
Impaired Conjugation:
Inherited Mutations in UGT1 - Grigler-Najjar Syndrome (Type I and Type II)
Inherited polymorphisms in UGT1 - Gilbert Syndrome
Cause of Conjugated Hyperbilirubinemia
Hepatocellular Diseases Cause Decreased Secretion:
Cirrhosis
Acute Hepatitis (drugs, viral, alcohol)
Pregnancy
Drugs
Inherited Diseases:
Dubin-Johnson Syndrome (ABCC2 mutation)
Rotor Syndrome (SLCO1B1 and SCLO1B3 mutations)
Biliary Obstruction: Gallstones Tumors Primary Biliary Cirrhosis Sclerosing Cholangitis
“Physiological Neonatal Jaundice”
Results from immaturity of ALL steps in bilirubin metabolism
Increased Production
Decreased Delivery
Decreased Uptake
High bilirubin level
BBB not great yet
Bilirubin in brain leads to kernicterus
Kernicterus
Brain damage due to bilirubin deposition
Treatment of Neonatal Jaundice
Phototherapy
Biliblankets or Bililight
Convert Natural Bilirubin to Photobilirubin (can pee out)
Jaundice
At “50”, you can glow in the dark