Alcohol Metabolism

Question 1

Explain the ADH pathway

Answer 1

• ethanol → acetaldehyde (by alcohol dehydrogenase enzyme)
• Acetaldehyde → acetate (by aldehyde dehydrogenase)
• Acetate → Acetyl CoA
• Acetyl CoA → CAC → ketogenesis/ lipolysis

Question 2

Explain the MEOS system

Answer 2

• only occurs in hepatocytes
• mediate by cytochrome (CYP2E1)
• requires oxidation of NADPH to NADP+ and consumes ATP
• Produces free radicals

Question 3

Explain the Catalase pathway

Answer 3

• oxidation occurs via peroxisomes
• uses hydrogen peroxides to form acetaldehyde and H20
• then acetaldehyde produces same outcomes as ADH pathway

Question 4

Factors Impairing Alcohol Metabolism

Answer 4

• ethnicity, age, gender

- poor alcohol dehydrogenase activity

Question 5

Build up of what causes a headache?

Answer 5

Acetaldehyde

Question 6

What is BAC

Answer 6

Blood alcohol content which is expressed as an percentage of ethanol in the blood

Question 7

How fast does the liver break down alcohol?

Answer 7

At a rate of 5-10 grams per hour (depending on gender)

Question 8

What is Guideline 1?

Answer 8

Reduce risk of alcohol-related harm over the lifetime

Question 9

What is guideline 2?

Answer 9

Reducing the risk of injury on a single occasion of drinking

Question 10

What is Guideline 3?

Answer 10

For children and people under 18, drinking alcohol is not safe

Question 11

What is Guideline 4?

Answer 11

Maternal alcohol consumption can harm the foetus or breastfeeding child

Question 12

What are the benefits of moderate alcohol consumption?

Answer 12

• Appetite stimulant (good for some people)
• Red wine contains antioxidants
• Suppresses proliferation of smooth muscle cells and thus reduces arterial stiffening
• Improves insulin sensitivity

Question 13

What is Alcoholic Ketoacidosis

Answer 13

• In the ADH pathway NAD is reduced to NADH
• Increased NADH/NAD ratio interferes with normal
  mitochondrial and CAC function, and impairs gluconeogenesis

Question 14

What are the 3 stages of chronic alcohol abuse

Answer 14

STAGE 1: steatosis (alcoholic fatty liver => reversible by
abstinence)
• STAGE 2: alcoholic hepatitis => reversible with abstinence
• STAGE 3: cirrhosis – not reversible. Loss of hepatocytes
function as the liver tissue is scarred: cirrhosis; liver failure; hepato-cellular carcinoma

Question 15

What is the J curve and what does it say?

Answer 15

That health benefits are associated with 1 standard drink are increased, but with more than one standard, the health risks are higher

Question 16

What are typical acute effects of alcohol abuse?

Answer 16

Dizziness, slurring, vomiting, low blood sugar, dehydration, unconsciousness

Question 17

What are the chronic effect of alcohol abuse on the liver?

Answer 17

Varying stages of liver disease: alcoholic fatty liver, alcoholic hepatitis, cirrhosis (irreversible)

Question 18

What causes Cirrhosis?

Answer 18

• increased conc of acetaldehyde
• accumulation of fat in liver causing cellular inflammation
• production of free radicals from metabolism, of alcohol

Question 19

What is Wernicke-Korsakoff syndrome?

Answer 19

A thaimin deficiency due to:

• decreased thiamin intake and absorption
• increased thiamin excretion in urine