18: Hepatobiliary Function Flashcards
Two main components f bile
Bile salts and phospholipids
NTCP and OATP1B1 function
Transport bile salts from blood -> hepatocyte
Na dependent and independent transporters for bile from blood into hepatocyte
NTCP: Na-dependent
OATP: Na-independent
Two mechanisms that cause bile secretion
- Most bile: driven by bile acids, as bile as secreted into canaliculi, cations passively follow
- Small portion due to secretin -> stimulates bicarb and water into bile
What inhibits cholesterol 7a hydroxylase in negative feedback
Bile salts
Five treatments for Crigler-Najjar syndrome
- Phototherapy
- Blood transfusions
- Oral Ca PO3 and carbonate
- Liver transplant
- Phenobarbital
How excess alcohol leads to sirrhosis
Alcohol -> fatty liver -> steatohepatitis -> scarring of liver / cirrhosis
What causes portal hypertension
Cirrhosis
Two things that occur with portal hyptertension
- Esophageal varices
2. Caput medusae
Hepatic encephalopathy
Decreased urea cycle in liver -> accumulation of ammonia in circulation -> ammonia readily crosses BBB to alter brain function
What is jaundice a sign of?
Hyperbilirubinemia
Physiological neonatal jaundice
Increased unconjugated bilirubin in blood first week post-natal
Two main causes of physiological neonatal jaundice
- Bilirubin production elevated from increased breakdown of fetal RBCs
- Low ADP glucuronyl transferase activity
How does phototherapy work for jaundice?
Isomerizes trans-bilirubin to water-soluble cis-bilirubin
Two types of liver function tests
Biochemical and function tests
Biochemical tests
Liver enzyme counts - ALT and AST, alkaline phosphatase
What does elevated aminotransferases mean? (ALT and AST)
Hepatocyte injury
What does elevated alkaline phosphatase mean?
Bile duct injury
Three main function tests for the liver
Bilirubin, albumin, PT (prothrombin time)
Bilirubin test
Measures livers ability to detox metabolites and transport organic anions into bile
Albumin test
If hepatocytes are severely impaired, albumin in plasma will be low (albumin synthesized exclusively in liver)
Hypoalbuminemia can also be seen in what?
Kidney disease?
PT test
Reflects hepatic synthetic function
When is PT high?
When cirrhotic liver loses ability to synthesize clotting factors?
