Liver practical Flashcards
What are the functions of the liver?
Major site of intermediary metabolism
Synthesis of important compounds
Conjugation/detoxification of natural and potentially toxic foreign substances
Storage of glycogen
What are liver cells called?
Hepatocytes
What does damage to hepatocytes cause?
Acute release of intracellular constituents into the blood stream
What does ALT stand for?
Alanine aminotransferase
What does AST stand for?
Aspartate aminotransferase
Where are AST and ALT found?
AST = mitochondria and cytoplasm
ALT = just cytoplasm
When are levels of ALT higher than AST?
When cytoplasmic damage is present, where few cells are totally destroyed (such as hepatitis)
When are levels of AST higher than ALT?
When damage effects the whole cell
Does AST or ALT have a longer half life?
ALT
So raised levels often persist for a longer time
What can the ratio of AST to ALT determine?
alcoholic vs non-alcoholic fatty liver disease
What does ALT catalyse?
Transfer of alpha-amino group from L-alanine to alpha-ketoglutarate
What are the products after ALT catalyses?
Glutamate and pyruvate
How do we determine activity of ALT?
React pyruvate with 2,4-dinirophenylhydrazine
Produces a coloured hydrazone that can have it’s absorbance measured
How does AST catalyse it’s reaction differently to ALT?
Transfers the animo group from L-aspartate
Results in oxaloacetate instead of pyruvate
What are normal levels of ALT and AST?
ALT = 5-40 U/L
AST = 5-45 U/L
