Alcohol Metabolism

Question 1

How is alcohol removed from the body?

Answer 1

90% metabolised by the liver, Remainder excreted passively in urine and on breath

Question 2

What is the main process of alcohol metabolism?

Answer 2

• Alcohol oxidised by alcohol dehydrogenase to acetaldehyde, converting NAD + to NADH
• Acetaldehyde oxidised to acetate by aldehyde dehydrogenase,converting NAD + to NADH
• Acetate converted into acetyl~CoA

Question 3

What happens to the acetyl~CoA produced in alcohol metabolism?

Answer 3

Used in TCA cycle or for fatty acid synthesis

Question 4

How can smaller amounts of alcohol be metabolised?

Answer 4

• Oxidised by cytochrome P450 2E1 enzyme (CYP2E1)
• By catalase in the brain

Question 5

What are the recommended maximum units of alcohol?

Answer 5

• 21 units per week for men
• 14 units per week for women

Question 6

How much is 1 unit of alcohol?

Answer 6

8g

Question 7

At what rate is alcohol metabolised?

Answer 7

Eliminated at a rate of ~7g

Question 8

What relationship does alcohol metabolism show?

Answer 8

0 order kinetics- linear elimination

Question 9

What causes a hangover?

Answer 9

Accumulation of the toxic metabolite acetaldehyde

Question 10

How is acetaldehyde toxicity normally kept to a minimum?

Answer 10

By aldehyde dehydrogenase

Question 11

Does aldehyde dehydrogenase have a high or low Km for acetaldehyde?

Answer 11

Low

Question 12

What does excess acetaldehyde cause?

Answer 12

Liver damage

Question 13

What can cause sufficient acetaldehyde accumulation to cause liver damage?

Answer 13

Prolonged and excessive alcohol consumption

Question 14

What effect can excess NADH and acetyl~CoA have on the liver?

Answer 14

Can lead to changes in liver metabolism

Question 15

What conditions can be caused by liver damage?

Answer 15

• ‘Fatty liver’
• Alcoholic hepatitis
• Alcoholic cirrhosis

Question 16

What is fatty liver caused by?

Answer 16

NAME?

Question 17

Why does increased synthesis of triacylglycerol occur in due to excessive alcohol consumption?

Answer 17

Because there is increased synthesis of fatty acids and ketone bodies because of increased acetyl~CoA (as is the end product of alcohol metabolism), and inadequate NAD + for fatty acid oxidation as decrease inNAD + /NADH ratio

Question 18

What has happened in lactic acidosis?

Answer 18

Lactate has accumulated in the blood

Question 19

Why does lactate accumulate in the blood in chronic alcohol consumption?

Answer 19

Because inadequateNAD + for conversion of lactate to pyruvate

Question 20

What is gout?

Answer 20

When urate crystals accumulate in tissues

Question 21

Why does chronic alcohol consumption cause gout?

Answer 21

Because of the kidneys inability to excrete uric acid is reduced because of inadequateNAD + conversion of lactate to pyruvate (uric acid and lactate share a common excretion pathway)

Question 22

How does chronic alcohol consumption cause hypoglycaemia?

Answer 22

Gluconeogenesis deficit, because inadequateNAD + for conversion of lactate to pyruvate and for glycerol metabolism

Question 23

What can be used to treat alcohol dependance?

Answer 23

Disulfiram

Question 24

What does disulfiram do?

Answer 24

Inhibits aldehyde dehydrogenase

Question 25

What happens if a patient on disulfiram drinks alcohol?

Answer 25

Acetaldehyde will accumulate, causing symptoms of hangover

Question 26

How is disulfiram administered?

Answer 26

Implanted into patient