B5-017 Hepatic and Gallbladder Physiology Flashcards
large capillary betwen plates of hepatocytes
liver sinusoids
drains filtered blood into hepatic vein and IVC
central vein
polarized parenchymal cells
hepatocytes
bile duct epithelial cells
cholangiocytes
liver resident macrophages
Kupffer cells
fenestrated endothelial cells
sinusoidal endothelial cells
- stores fat soluble vitamins
- produces collagen
stellate cells
what types of metabolism occur in zone 1?
3
- fatty acid oxidation
- gluconeogenesis
- bile acid uptake
what types of metabolism occur in zone 2?
- fatty acid synthesis
- glycolysis
- bile acid synthesis
prevents reflux of duodenal contents into the pancreatic and bile ducts
spincter of Oddi
three organic solutes important to bile formation
- cholesterol
- bile salts
- phospholipids
- glycosylated protein forming gel lubrication barrier
- found in bile
mucin
proteins found in bile
4
- IgA, IgM, IgG
- mucin
- albumin
- apolipoproteins
precursor of sex hormones, arenal hormones, vitamin D, and bile acids
cholesterol
hepatic cholesterol sources of input
diet
de novo synthesis
hepatic cholesterol output
biliary secretion and bile acid synthesis
rate limiting enzyme in cholesterol formation
HMG CoA reductase
statins inhibit
major CYP pathway of cholesterol -> bile acid synthesis
CYP7A1
primary bile acids
2
CDCA
CA
secondary bile acids
2
DCA
LCA
how much bile acid is eliminated through feces?
%
5%
how much cholesterol is eliminated through feces?
%
50%
secretion via I cells is stimulated by dietary fats and amino acids
CCK
- stimulates gallbladder contraction
- relaxes spinchter of Oddi
CCK
- inhibits gastric secretion to promote digestion
- induces satiety
CCK
stimulates HMG CoA reductase and LDLR to increase de novo cholesterol synthesis and uptake of lipoprotein
during low cholesterol
SREBP2
stimulates ABCG5/G8 and CYP7A1 to increase cholesterol catabolism and secretion
during high cholesterol
LXR
induces FGF19 to inhibit CYP7A1 in hepatocytes
bile-acid activated FXR
bile activated FXR induces […] to increase bile acid secretion
BSEP
bile activated FXR induces […] to promote bile acid transport
OST/aB
bind negatively charge bile acids to prevent bile acid reabsorption
bile acid sequestrants
defects in micelle synthesis will cause
2
hypercholesterolemia
artherosclerosis
defects in the hepatic transport of mixed micelles will cause
cholestasis
defects in intestinal absorption with mixed micelles cause
chronic diarrhea