Lecture 34 Flashcards
What is ethanol? What is its fuel value and what is it converted to?
Ethanol is alcohol and has a fuel value of roughly 29 Kj/g, it is a potential toxin. It is absorbed relatively quickly into the bloodstream but leaves slower as it is acted upon by alcohol dehydrogenase in a reaction which converts ethanol to acetaldehyde (CC=O vs CC-OH) and during this reaction NAD+ is reduced to NADH. This acetaldehyde is converted to acetate via aldehyde dehydrogenase (CC=O to CC(O-)=O) and reduces another NAD+ to NADH.
What are the levels in the blood of the ethanol intermediates?
The levels in the blood will be ethanol highest, then acetate and lastly acetaldehyde.
What does acetyl CoA synthetase do?
Acetyl CoA synthetase will combine the acetate with CoA into acetyl CoA with the usage of ATP to AMP and PPi, this can then be used for the citric acid cycle, and hence electron transport and oxidative phosphorylation, it could also be stored in the liver, leading to stetosis (fatty liver).
What is the problem with the ethanol pathway?
The ethanol pathway doesn’t really stop (leading to increased NADH and ATP levels), this can lead to slowing of the citric acid cycle, electron transport, pyruvate dehydrogenase, glycolysis and fatty acid oxidation, it also causes pyruvate to convert to lactate and hence lowers pH and inhibits gluconeogenesis (low blood glucose and coma). Esterification of fatty acids to TAG.
What is the other pathway for ethanol? Why are there possible side effects?
Ethanol can also be oxidised via an oxidase, this converts NADPH + O2 to 2H2O and the ethanol to acetaldehyde. This can also metabolise other drugs, somes leading to adverse reactions.
What can chronic alcohol metabolism lead to?
Chronic alcohol metabolism leads to: toxic levels of acetaldehyde, reactive oxygen species, these lead to fatty liver and inflammation which can lead to alcohol hepatitis, then necrosis which leads to cirrhosis and finally coma and death.
