Alcohol Metabolism Flashcards
Where does energy come from?
Ingest energy from food, the energy in chemical bonds come from the sun/photosynthesis
We use the energy as fuel and break it down into sugars, fatty acids and amino acids. From the breakdown we get C and N and micronutrients
What is the GABA receptor
Affects of alcohol mediated by GABA receptor, neurotransmitter made from glutamate, GABA binds to GABA receptor and changes processes in the brain, ethanol binds to receptor and amplifies the effect of chloride channel which causes inhibitory affect on neurotransmission, reducing chance of successful action potential
Activation of receptor dampens down response to other stimuli
What is alcohol and how is it removed?
Ethanol as a fuel gives you 29kJ/g of energy if it is metabolised however too much makes it a potential toxin
Steady decrease of blood alcohol concentration (BAC) over moderate period of time, 10g/hr - alcohol being removed by liver
What is alcohol dehydrogenase?
Alcohol dehydrogenase oxidises ethanol into acetaldehyde, reducing power from NAD. Acetaldehyde very reactive, damages proteins and effects (if builds up causes hangover)
Only takes a couple of drinks to saturate alcohol dehydrogenase, 1-2 drinks mmol/L above Km and driving enzyme to Vmax
What is aldehyde dehydrogenase?
Aldehyde dehydrogenase oxidises acetaldehyde to acetate, reducing power from NAD+ to NADH + H+
Aldehyde dehydrogenase rapidly removes acetaldehyde to minimise toxic affects
What is acetyl CoA synthetase?
Acetyl CoA synthetase uses energy to drive acetate to acetyl CoA which can be fed into CAC and be metabolised however if you’re not in need to ATP, acetyl-CoA goes into the fatty liver and is stored in adipose tissue as fat
What happens if you drink too much alcohol?
If you overwhelm capacity of VLDL, by drinking too much alcohol, for storage in adipose tissue you will build up fatty acids in the liver itself resulting in fatty liver/steatosis which damages liver tissue and produces scar tissue and cysts
What affects does drinking alcohol have on metabolism?
With ethanol there is rapid production of acetyl-CoA, the steps of ethanol to acetyl CoA do not have a feedback mechanism resulting in consequences, build up of acetyl CoA and lead to fatty liver, slow down flux of glycolysis which drives reaction of amino acids to give you lactate= acidic in blood
What are the consequences of alcohol metabolism?
Increased NADH and ATP, slows citric acid cycle, electron transport, pyruvate dehydrogenase, glycolysis and fatty acid oxidation
Fatty acids esterified to TAG which causes fatty liver and can also result in hypercholesterolaemia and hypertriacylglycerolaemia
What is the consequence of increased NADH?
Causes pyruvate to be converted to lactate which decreases pH levels in blood and inhibits gluconeogenesis which can cause low blood glucose and coma
What is the microsomal ethanol oxidising system?
If you drink more frequently you can develop a metabolism that will metabolise alcohol faster using oxidase enzyme to convert ethanol to acetaldehyde however the oxidase can also give rise to reactive oxygen species resulting in adverse reactions with drugs etc.
How does chronic alcohol metabolism lead to coma and death?
Chronic alcohol metabolism -> toxic acetaldehyde and reactive oxygen species -> fatty liver; inflammation -> alcoholic hepatitis -> necrosis -> cirrhosis -> coma and death
