Liver and LFTs Flashcards
(67 cards)
What are the two blood supplies of liver
portal vein and hepatic arter
75% portal vein
Where is bile formed from and what is its passage out of the liver
Bile is formed from the hepatocytes, flows through bile canaliculi to bile duct (⇒ flow is opposite to blood)
Where does blood in central veins go to
Blood collected in central veins goes to sublobular veins, then to collecting veins, and then hepatic veins leaving the liver
What maintain pressure within common bile duct
Ampulla of vater/ sphincter body
Pressure there should usually be higher than that of gallbladder
What causes gallbladder contraction (what hormone is involved)
Cholecystokinin release from mucosa in duodenum during feeding causes gallbladder contraction, reduced sphincter pressure on bile and allows bile to flow from gall bladder to duodenum
What are cholangiocytes
Bile duct epethelia, contribute to cell function
What forms the sieve plate in liver
Endothelial cells
Sinusoidal vs lateral faces in hepatocytes
- Microvilli are present on sinusoidal face to project sparsely into bile canaliculi
- A portion of the lateral faces of hepatocytes is modified to form bile canaliculi
Where are glycogen granules stored in hepatocytes
In association with SER
Difference between periportal and perivenous/pericentral zone in liver acinus
Periportal has good o2 supply and nutrient rich, involved in gluconeogenesis, glycogenolysis and bile salt formation, perivenous involved in glycolysis, lipolysis, glucuronidation, glycogenesis and cytochrome p450 reaction. Low in nutrients and relatively hypoxic
Three phases of biotransformation
I - oxidation, reduction and hydrolysis by CYP450
II- Conjuation in cytoplasm with endogenous substances like glucuronic acid to form inactive conjugates
III- secretion into bile, excretion mediated by ATP
What can conjugate with drugs in phase II metabolism
Gluthatione for oxidated species
or sulfur, acetyl or glucuronide for hydrolysed species
Glutathione conjugation in paracetamol metabolism??
Bonds with NAPQI to form non-toxic conjugates
What does N-acetyl cysteine do
Increases Glutathione to mop up NAPQI
What causes alcohol flush response
Deficiency in ALDH-2 ( Aldehyde dehydrogenase) that results in increased acetylaldehyde and catecholamine release
What happens to insulin and glucagon after feeding and main actions in liver
Increased insulin and decreased glucagon
- Hepatic glucose uptake
- Glycogen deposition in hepatocytes
- Glucose converted into glycerol and fatty acids
What happens to insulin and glucagon in fasting and main actions in liver
Reduced insulin and increased glucagon
- Glycogen breakdown in periportal hepatocytes
- Gluconeogenesis from lactate, pyruvate, AA, glycerol
Synthesis of lipids in liver
Liver also synthesizes VLDL and HDL
Also synthesises cholesterol and phospholipids, some of which is secreted into bile and some is converted into bile acids
What transport proteins are synthesised in liver
ceruloplasmin to transport copper and transferrin which transports iron
Which enzymes synthesized in liver require vitamin K
II, VII, IX, X are post-translational modified by Vitamin K dependent enzymes ⇒ synthesis impaired by VItamin K deficiency
How is unconjugated bilirubin formed
from breakdown of heme in spleen
Where does bilirubin get conjugated and by what
By glucuronyl billirubin transferase in liver
What does direct bilirubin get converted to and where
To urobilinogen in duodenum by microbiome, then to stercobilin
What vitamins stored in large amounts in liver
A, D, B12
