Alcohol

Question 1

Define a UK unit of alcohol

Answer 1

1 unit = 8 g of alcohol

Question 2

Give examples of how many UK units of alcohol are found in beverages

Answer 2

125 ml wine = 1 unit Half a pint beer/larger = 1 unit 25 ml spirit = 1 unit

Question 3

Describe why knowledge of alcohol in the body is important

Answer 3

2nd largest psychoactive drug in use. Sedative. Energy: 7 kcal/gram 1-2 units per day associated with health benefits

Question 4

Describe how alcohol enters the body with an emphasis on the circulation

Answer 4

Alcohol can cross the cell membrane (plasma, BBB, placenta) Almost always oral. Absorbed from the intestine via diffusion

Question 5

Give examples of the metabolic consequences of oxidative phosphorylation of ethanol

Answer 5

• Breakdown of alcohol produces NADH
• NADH enters into oxidative phosphorylation (electron donor)
• This then inhibits the TCA cycle - as energy is being produced via use of alcohol generated NADH
• Pyruvate metabolism is decreased, due to lack of oxaloactate (allows entry into the TCA cycle)
• Ketone bodies are produced as pyruvate is converted into ketones

☆ Acetaldehyde forms Schiff bases. Changes the nature of the protein, leading to fibrosis

Question 6

Explain how ethanol is metabolized to carbon dioxide and water

Answer 6

Alcohol – (alcohol DH) –> acetaldehyde – (acetaldehyde DH) –> acetate – oxidising enzymes –> water and CO2 ALDH is the rate limiting step.

Question 7

Explain how genetic difference in ADH and ALDH change ethanol metabolism

Answer 7

Women have decreased levels of ADH in the stomach. Asian populations have decreased ALDH, increased build-up of acetaldehyde. Increased unpleasant effects. Europeans have higher levels of ADH

Question 8

Explain how ADH and ALDH inhibitors change ethanol metabolism

Answer 8

ADH can be inhibited by pyrazole or antizol/fomepizol

ALDH act be inhibited by disulfiram. Causes nausea etc. discourages drinking.

Question 9

Explain how ADH/ALDH metabolism of ethanol inhibits metabolism of other energy producing metabolites

Answer 9

Hypoglycaemia: Decreased gluconeogenesis and increases glycolysis

Acidosis: Increases conversion of pyruvate to lactate

Steatosis: Fatty accumulation in the liver as liponeogenesis is increased whilst fatty acid oxidation is decreased.

Question 10

Rate limiting step

Answer 10

Alcohol dehydrogenase activity: Acetaldehyde, produced by ADH, is the toxin associated with the unpleasant affects of alcohol consumption.

• Rate limiting step for producing the toxic effects

ALDH activity: Rate limiting step for detoxifiying acetaldehyde effects

Question 11

Effects on ethanol on the CNS

Answer 11

• With increasing concentrations the effects on the CNS become greater
• Has specific and non-specific effects
• Suppresses calcium ion currents
• Causes alterations in cAMP and Na⁺ pumps