3. Alcohol metabolism (new)

Question 1

what is the energy content of alcohol

Answer 1

29 kJ/g

Question 2

where is alcohol mostly metabolised

Answer 2

liver

Question 3

describe the catabolism of alcohol

Answer 3

1. alcohol oxidation to acetaldehyde by alcohol dehydrogenase
2. acetaldehyde oxidation to acetate by aldehyde dehydrogenase
3. acetate converted to acetyl-CoA by binding to CoA - use in TCA cycle and FA synthesis

Question 4

what is the most toxic alcohol metabolite and how is toxicity usually prevented

Answer 4

acetaldehyde

aldehyde dehydrogenase has low Km so quickly oxidises acetaldehyde to acetate

Question 5

give 3 reasons for the toxic effect of alcohol on liver

Answer 5

1. direct toxicity of aldehyde - hepatocyte membrane damage and enzyme leakage
2. decreased NAD+/NADH ratio affects liver metabolism
3. increased acetyl-CoA affects metabolism

Question 6

give 3 signs of liver damage caused by the toxic effects of acetaldehyde

Answer 6

1. jaundice (decreased uptake/conjugation of bilirubin)
2. oedema (decreased albumin synthesis)
3. fatty liver (decreased lipoprotein synthesis and lipid transport from liver)

Question 7

name 4 physiological effects of decreased NAD+:NADH ratio

Answer 7

1. lactic acidosis (inadequate NAD+ for lactate conversion to pyruvate) and gout (decreased kidney ability to excrete uric acid)
2. fasting hypoglycaemia (inadequate NAD+ for glycerol metabolism so gluconeogenesis deficit)
3. fatty liver (inadequate NAD+ for FA oxidation)

Question 8

what are the effects of increased acetyl-CoA on the liver

Answer 8

fatty liver due to increased FA synthesis and conversion to TAGs

Question 9

name a drug used as an adjunctant in alcoholism treatment

Answer 9

disulfiram

Question 10

what is the MOA of disulfiram

Answer 10

aldehyde dehydrogenase inhibitor so accumulation of acetaldehyde and hangover