Alcohol Metabolism

Question 1

Liver damage

Answer 1

• acetaldehyde toxicity 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 lead to changes in liver metabolism
  Fatty acid, alcoholic hepatitis, alcoholic cirrhosis

Question 2

Alcoholic consumption

Answer 2

Lactic and Uric acid share the same excretory pathway

• irate crystals accumulate in tissues producing GOUT
• insufficient pyruvate fro gluconeogenesis
• lower lipoprotein synthesis - liver cannot export fat via LDLs - fatty liver

Question 3

Treatment of alcohol dependence

Disulfiram

Answer 3

• blocks aldehyde dehydrogenase

- if patient drinks alcohol acetaldehyde will accumulate causing symptoms of a hangover

Question 4

Alcohol metabolism 
(by zero order kinetics - linear - 7g/hr constant rate)

Answer 4

90% metabolised by liver (remained excreted in urine and on breath)
- alcohol oxidised by alcohol dehydrogenase to acetaldehyde and then to acetate by aldehyde dehydrogenase
- acetate converted to acetyl-CoA and used in TCA cycle or for FA synthesis
- smaller amounts can be oxidised by the cytochrome P450 2E1 enzyme or by catalase in the brain
RECOMMENDED LIMITS
- 21 units a week/ 4 units per day for men
- 14 unit a week/ 3 units per day for women
One unit = 8g of ethanol