Liver Biochemistry Flashcards
(47 cards)
What is the structure of the liver?
4 lobes: right, left, caudate, quadrate
What is the blood supply to the liver?
The hepatic portal vein - brings nutrient-rich venous blood from GI tract (75%) hepatic arteries (25%)
What are the cells of the liver? (6)
hepatocytes endothelial cells hepatic stellate cells cholangiocytes pit cells kupffer cells
What is the function of hepatocytes?
They’re the main cell type in the liver (80%), carry out metabolic liver functions.
CAN REGENERATE
What is the function of liver endothelial cells?
Allow exchange b/w liver and blood via pores & fenestrations in their plasma membrane
What is the function of hepatic stellate cells?
Are storage site for Vitamin A and other lipids
What is the function of cholangiocytes?
They line the bile duct, control bile flow rate and bile pH
What is the function of pit cells?
These are NK cells that protect liver from viruses and tumors (lymphocytes)
What is the function of Kupffer cells? (4)
- Protect liver from gut-derived microbes
- Remove dead cells
- orchestrate immune response
- secrete cytokines
Line the sinusoids. Are specialized macrophages w/good endocytic & phagocytic function and lots of lysosomes
What are the general functions of the liver? (8
- Carbohydrate metabolism
- Lipid metabolism
- Nucleotide biosynthesis
- Protein and amino acid metabolism
- Removal of nitrogen generated by protein & aa metabolism
- Bilirubin metabolism
- Synthesis of blood proteins
- Deactivates/detoxes/biotransforms metabolites and xenobiotics
What specifically does the liver do in carbohydrate metabolism? (6)
Glucostasis (keep blood gluc stable) Glycogen synthesis Glycogenolysis Gluconeogenesis Makes ketones when starving Has Glucose-6-phosphatase to release free gluc to blood
What does the liver do in lipid metabolism? (3)
Biosynthesizes fats
Degrades fats
Regulates FFA Metabolism (making and breaking)
What proteins does the liver synthesize? (7)
Acute phase proteins - CRP - protease inhibitors - alpha-1 antitrypsin - alpha-1 antichymotrypsin albumin IgG apoproteins fibrinogen prothrombin clotting factors V, VII, IX, X
What ways has the liver adapted to facilitate its function? (3)
circulation
structural
cellular
What circulatory adaptations does the liver have to facilitate its function?
It gets blood from enteric circulation and the periphery so it can have first pass for ingested substances
What structural adaptations does the liver have to facilitate its function?
- No basement membrane
- No tight junctions b/w hepatocytes and endothelial cells
- gaps b/w endothelial cells
- pores in endothelial membrane
Basically all this to allow more contact between the liver and blood
What cellular adaptations does the liver have to facilitate its function?
Well-developed plasma membrane and ER, lots of lysosomes and metabolic enzymes
What are the steps of emulsification? (4)
- cholic acid (bile acid) ionizes to give bile salt
- hydrophobic surface of bile salt associates w/TAG, several complexes aggregate to form micelle
- hydrophobic surface of bile salt faces out, allows micelle to interact w/ pancreatic lipase
- hydrophobic action of lipase frees FA’s to break into smaller micelle that’s absorbed through intestinal mucosa
What are the primary bile acids?
- chenodeoxycholic acid
- cholic acid
What are the secondary bile acids?
- deoxycholic acid
- lithocholic acid
What is the difference between primary and secondary bile acids?
Primary - synthesized in liver
Secondary - result from bacterial action in colon. Also have no -OH on carbon 7. They inhibit 7 alpha-hydroxylase!
What are gallstones?
Supersaturated gallbladder bile with cholesterol crystals
What can cause gallstones? (3)
- inefficient bile salt secretion
- inefficient phospholipid secretion
- excess cholesterol secretion
What is the treatment for gallstones? (2)
If too big, cholecystectomy
If small enough, can treat with oral ursodeoxycholic acid, a secondary bile acid that reduces cholesterol secretion, increases biliary cholesterol solubility
