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Biochem Block 3 > ethanol metabolism > Flashcards

ethanol metabolism Flashcards

1
Q

calories from ethanol

A
  • 4th major nutrient that provides energy
  • empty calories because they have no nutritional value
  • 98 grams per drink for ethanol only!
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2
Q

lifestyle choice death

A
  1. smoking
  2. obesity
  3. alcoholism
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3
Q

alcoholism is the IMMEDIATE cause of what?

A

-liver cancer

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4
Q

What is the first organ effected by alcoholism?

A

liver

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5
Q

why is ethanol easily absorbed by intestine and readily entered into the blood stream?

A
  • water and fat soluble

- requires no digestion or enzymes to break it down

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6
Q

why do we have an enzyme that specifically works on alcohol?

A

-intestinal flora use fermentation so we developed the enzyme to handle ethanol

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7
Q

Majority of ethanol is matabolized…

A

in the liver by two different pathways

  1. ADH
  2. MEOS using cyt-P450 enzymes
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8
Q

ADH system

A
  • does not use energy
  • ADH makes toxic acetaldehyde, ALDH turns that into acetate
  • acetate goes into blood then goes to acetyl CoA in muscles for TCA cycle
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9
Q

what is the rate-limiting step in ADH system?

A

-ADH (alcohol dehydrogenase)

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10
Q

What is the limiting factor for alcohol metabolism?

A

-NAD+ availability

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11
Q

Zero order kinetics

A

-a constant amount of drug is eliminated per unit of time

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12
Q

Km of ADH

A
  • 1mmol/L
  • saturated after one drink
  • if you continue to drink, it stays in the blood stream until the enzyme is done breaking down the first drink
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13
Q

generally, people metabolize…

A

10g of alcohol per hour

-blood alcohol level decreases 0.15g/L every hour

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14
Q

atypical ALDH

A
  • eat asians
  • single amino acid substitution (Glu to Lys)
  • dominant negative
  • oriental flush
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15
Q

What accumulates with atypical ALDH?

A
  • toxic acetaldehyde

- cant turn it into acetate

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16
Q

Disulfiram

A
  • inhibits aldehyde dehydrogenase(ALDH)
  • accumulation of acetaldehyde
  • used in treatment for alcoholics
17
Q

What happens if a person keeps drinking past the pain on disulfiram?

A

-damage caused by acetabldehyde that is seen in long time alcoholics will be ACCELERATED

18
Q

processing of alcohol produces a large amount of…

A

NADH in the liver

19
Q

Why is a build up of NADH so bad?

A
  • can alter many metabolic processes

- significant effects are found in heavy drinkers of binge drinkers

20
Q

build up of NADH in well fed state

A
  • liver is taking up glucose and performing glycolysis, producing NADH and pyruvate
  • adding more NADH to this amount will inhibit PDH complex and force it into pyruvate
  • lactic acidosis and hyperuricemia
21
Q

build up of NADH in fasting state

A
  • liver will try to perform GNG, but NADH inhibits it so it is diverted to lactate
  • hypoglycemia
22
Q

is alcohol a substrate for GNG?

****

A
  • nope

- it is ketogenic, not glucogenic

23
Q

hyperlipidemia

A
  • NADH inhibits oxidation of fatty acids
  • accumulation of TAG as liquid droplets
  • fatty liver disease which can lead to hyperlipidemia
24
Q

Acetyl CoA and build up of NADH

A
  • NADH inhibits TCA cycle
  • OAA is converted back into malate to generate NAD+
  • Acetyl CoA is forced into ketone synthesis and can result in ketoacidosis
25
Q

free radical production

A
  • induction of cyt-P450 produce more free radicals and therefore, more damaged cells
  • acetaldehyde is a reactive compound that limits cells ability to neutralize free radicals
  • results in cirrhosis and liver failure
26
Q

megaloblastic anemia

A

-folate deficiency

27
Q

what deficiency causes wernicke-korsakoff syndrome?

A

-thiamine deficiency

28
Q

Wernicke’s encephalopathy

A
  • damage is not permanent and can be reversed with supplements
  • confusion, tremors, vision problems
29
Q

Korsakoff syndrome

A
  • progression of wernicke
  • memory loss, hallucinations
  • irreversible and permanent brain damage
30
Q

FASD

A
  • fetal alcohol spectrum disorder
  • disorders caused by prenatal alcohol exposure
  • first three months are especially harmful
31
Q

FASD mechanism

A
  • prego lady has depressed alcohol metabolism because estrogens inhibit ADH
  • fetal metabolism is even worse, so alcohol stays in the blood longer and causes oxygen problems

Biochem Block 3 (10 decks)

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