Alcohol Metabolism Flashcards
(23 cards)
Where is alcohol metabolised?
Liver
Roughly how much of alcohol is metabolised and what happens to the remainder?
> 90%, remainder excreted in urine or on breath
What enzyme oxidises alcohol to acetaldehyde?
Alcohol dehydrogenase
What enzyme converts acetaldehyde to acetate?
Aldehyde dehydrogenase
What is the acetate derived from alcohol converted to?
Acetyl CoA for use in TCA cycle or fatty acid synthesis
Smaller amounts of alcohol can also be oxidised by which enzymes?
Cytochrome P450 2E1 enzyme or catalase in brain
What are the recommended limits of alcohol per week?
14 units/week spread over at least 3 days for both men and women
How many grams of ethanol in one unit of alcohol?
8g
What is the rate of alcohol elimination?
7g per hour (roughly)
The accumulation of what molecule causes the symptoms of a hangover?
Acetaldehyde
What is also produced from the oxidation of ethanol to acetaldehyde and also the oxidation of acetaldehyde to acetate?
NADH (from NAD+)
Why does aldehyde dehydrogenase work at a high rate and usually keep acetaldehyde toxicity to a minimum?
Enzyme has a low m for acetaldehyde
What is cirrhosis?
Cirrhosis is scarring of the liver caused by continuous long-term liver damage. Scar tissue replaces healthy tissue in the liver and prevents the liver working properly.
What causes liver damage?
Accumulation of acetaldehyde
What causes changes in liver metabolism?
Excess NADH and acetyl-coA
What is alcoholic hepatitis?
Inflammation of the liver due to excessive intake of alcohol
What initial two things does alcohol oxidation cause?
1) Decrease in NAD+/NADH ratio
2) Increase in Acetyl-CoA
What are the effects of the decreased NAD+/NADH ratio caused by alcohol oxidation?
1) Inadequate NAD+ for conversion of lactate to pyruvate
2) Inadequate NAD+ for glycerol metabolism
3) Inadequate NAD+ for fatty acid oxidation
What are the results of inadequate NAD+?
1) Accumulation of lactate - lactc acidosis, accumulation of urate crystals causing gout
2) Deficit in gluconeogensis - hypoglycaemia
3) Increased synthesis of triacylglycerol - fatty liver
What are the effects of increased acetyl-coA due to oxidation of alcohol?
Increased synthesis of fatty acids and ketone bodies, increased synthesis of triacylglycerol, fatty liver
What drug is used to treat alcohol dependence?
Disulfiram
What does disulfiram inhibit?
Aldehyde dehydrogenase
What are the effects of taking disulfirim?
If patient drinks alcohol, acetaldehyde will accumulate and cause symptom of a hangover. It therefore acts as a detterent.
