Alcohol Metabolism Flashcards
1
Q
whats the energy content of alcohol and where is it metabolised?
A
- 29KJ/g
- liver mainly, but some is excreted in the urine and on breath
2
Q
draw the equation and the enzymes involved in the metabolism of alcohol
A
- alcohol is oxidised to acetaldehyde by alcohol dehydrogenase which uses NAD+ and forms NADH and then it is converted into acetate by aldehyde dehydrogenase which uses NAD+ and forms NADH.. acetate is then conjugated to coenzyme A to form actyl-coA and metabolised in the TCA cycle or utilised for fatty acid synthesis
- smaller amounts of alcohol can be oxidised by cytochrome P450 2E1 enzymes (CYP2E!) or by catalase in the brain
3
Q
whats the recommended limit of alcohol and whats the rate of alcohol metabolism
A
- 14 units male and female
- one unit of alcohol = 8g / rate of elimination is 7g/hour
4
Q
whats causes the hangover reaction
A
acetaldehyde
5
Q
whats the km of aldehyde dehydrogenase and what happens if generally you have too much alcohol
A
- low km = high affinity for acetaldehyde which is very toxic
- too much alcohol means too much acetaldehyde which is toxic causing liver damage —> cirrhosis
- excess NADH and Acetyl-CoA leads to changes in lover metabolism resulting in fatty liver/ alcohol hepatitis / alcohol cirrhosis
- decrease in NAD+/NADH (too much NADH) so NAD+ not enough to convert lactate into pyruvate, so too much lactate in the blood causing lactic acidosis , and kidney’s ability to excrete uric acid reduced because uric acid and lactate use the same transporter, so too much lactate in the blood means it’ll use the transporter and not uric acid so urate crystals in the tissues causing gout
- also due to lactate not being converted to pyruvate you need to mobilise glycogen stores but not enough NAD+ for glycerol metabolism so deficits in gluconeogenesis resulting in hypoglycaemia
- inadequate NAD+ for fatty acid oxidation so increased synthesis of TAG which causes fatty liver since they cant be transported out the liver because the synthetic ability of live decreases over time due to oxidative stress from increased alcohol consumption
