Alcohol Metabolism Flashcards
What is the energy content in alcohol?
29KJ/g -This is higher than protein and carbs but not as much as fat.
Where is most alcohol metabolised?
The liver (+90%).
The remainder is passively excreted in urine and on breath.
What are the two main enzymes involved in alcohol metabolism?
Alcohol dehydrogenase - This converts ethanol to acetalaldehyde
Aldehyde dehydrogenase - This converts acetyldehyde into acetate
What are the recommended alcohol limits?
14 units per week spread over 3 days for both men and women.
What is the rate of alcohol metabolism?
about 7g/hr
(one unit of alcohol is about 8g so it is approx one unit per hour)
How does the body metabolise ethanol into acetaldehyde?
Using the conversion of NAD to NADH and the enzyme alcohol dehydrogenase
How does the body metabolise acetaldehyde to acetate?
Using the conversion of NAD to NADH and the enzyme aldehyde dehydrogenase
What causes a hangover and why?
The accumulation of acetaldehyde causes a hangover because it is toxic.
What happens after alcohol has been metabolised to acetate?
Acetate is conjugated to coenzyme A to form acetyl-`CoA which is then metabolsied in the TCA cycle or utilised for fatty acid synthesis.
What causes liver damage?
Acetaldehyde toxicity is normally kept to a minimum by aldehyde dehydrogenase (low Km for acetaldehyde).
Prolonged and excessive alcohol consumption can cause sufficient acetaldehyde accumulation to cause liver damage.
Excess NADH and Acetyl-CoA can lead to changes in liver metabolism.
What is liver cirrhosis?
Scaring of the liver. (As a result of fibrosis)
What three things can happen to the liver as a result of liver damage?
Fatty liver
Alcoholic Hepatitis
Alcoholic cirrhosis
What are metabolic resonses to chronic alcohol consumption?
Alcohol Oxidation which relsutls in insufficient NAD and increased Acetyl-CoA
Insufficient NAD results in:
Lactic Acidosis
Urate crystals accumulate in tissues producing gout
Hypoglycaemia.
Increased Acetyl-coA:
Results in increased synthesis of fatty acids and ketone bodies. This increases the synthesis off triacylglycerols. But, because there is inadequate NAD from fatty acid oxidation, it results in a fatty liver.
What is disulfiram?
Disulfiram is a drug that can be used to help treat chronic alcohol dependence.
This is an inhibitor of aldehyde dehydrogenase.
This means that acetaldehyde will accumulate and result in severe hangover symptoms. (Eg being sick).
