Endocrine Liver 1 Flashcards
What are the lipid soluble vitamins?
A, D, E, K (can be stored in liver)
How is Bilirubin modified in the liver?
conjugation (with glucuronic acid or sulfate) & excreted into bile
How does the liver process substrates (biotransformation)?
Phase I (oxidation, reduction, hydrolysis) “indirect” : by Cytochrome P-450; Phase II (conjugation to glucuronate, methyl group, sulfate, acetate, glycine, or glutathione) “direct”
How does the Na-dependent transporter work for hepatocyte intake?
driven by Na/K ATPase - pumps Na+ out and K+ in; creates gradient for Na/HCO3 or Na/AA symporters; Na/H+ exchange; and bile acid co-transporter (Na/BileSalt)
How does Na-independent transporter work for hepatocyte intake?
OATP (organic anion transport polypeptide) - for bile salts, organic ions, lipophilic coumpounds
GLUT-2
does not respond to insulin, uptake of glucose
Endocytosis
usually to lysosymes
What is Jaundice?
bilirubin accumulation
What are causes of Jaundice?
excess production/RBC destruction, decrease metabolism of bilirubin, decrease secretion in canaliculi, bile duct obstruction
How do hepatocytes transport their bile salts out and into canaliculi?
conjugate (for increased solubility) –> active ATP dependent transport to canaliculi. Bile flow in indirection toward portal triad
Bile Salt Export Pump
ATP dependent pumps against concentration gradient
MDR (multi drug resistance) Proteins 1, 2, & 3
transport of bilirubin, organic ion/cations, various drugs. Some drugs can result in jaundice for interfering with these transporters.
Methods of ATP independent export out of hepatocyte.
Cl- channel, Cl/HCO3 exchanger, & GSH glutathione transporter
Why do people with jaundice present with pale, greasy stools?
bile salts are needed for fatty digestion in intestine, and it’s not getting there.
