ethanol metabolism Flashcards Preview

Biochem Block 3 > ethanol metabolism > Flashcards

Flashcards in ethanol metabolism Deck (31):
1

calories from ethanol

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

2

lifestyle choice death

1.smoking
2.obesity
3.alcoholism

3

alcoholism is the IMMEDIATE cause of what?

-liver cancer

4

What is the first organ effected by alcoholism?

liver

5

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

-water and fat soluble
-requires no digestion or enzymes to break it down

6

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

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

7

Majority of ethanol is matabolized...

in the liver by two different pathways
1. ADH
2. MEOS using cyt-P450 enzymes

8

ADH system

-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

9

what is the rate-limiting step in ADH system?

-ADH (alcohol dehydrogenase)

10

What is the limiting factor for alcohol metabolism?

-NAD+ availability

11

Zero order kinetics

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

12

Km of ADH

-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

13

generally, people metabolize...

10g of alcohol per hour
-blood alcohol level decreases 0.15g/L every hour

14

atypical ALDH

-eat asians
-single amino acid substitution (Glu to Lys)
-dominant negative
-oriental flush

15

What accumulates with atypical ALDH?

-toxic acetaldehyde
-cant turn it into acetate

16

Disulfiram

-inhibits aldehyde dehydrogenase(ALDH)
-accumulation of acetaldehyde
-used in treatment for alcoholics

17

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

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

18

processing of alcohol produces a large amount of...

NADH in the liver

19

Why is a build up of NADH so bad?

-can alter many metabolic processes
-significant effects are found in heavy drinkers of binge drinkers

20

build up of NADH in well fed state

-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

build up of NADH in fasting state

-liver will try to perform GNG, but NADH inhibits it so it is diverted to lactate
-hypoglycemia

22

is alcohol a substrate for GNG?
************

-nope
-it is ketogenic, not glucogenic

23

hyperlipidemia

-NADH inhibits oxidation of fatty acids
-accumulation of TAG as liquid droplets
-fatty liver disease which can lead to hyperlipidemia

24

Acetyl CoA and build up of NADH

-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

free radical production

-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

megaloblastic anemia

-folate deficiency

27

what deficiency causes wernicke-korsakoff syndrome?

-thiamine deficiency

28

Wernicke's encephalopathy

-damage is not permanent and can be reversed with supplements
-confusion, tremors, vision problems

29

Korsakoff syndrome

-progression of wernicke
-memory loss, hallucinations
-irreversible and permanent brain damage

30

FASD

-fetal alcohol spectrum disorder
-disorders caused by prenatal alcohol exposure
-first three months are especially harmful

31

FASD mechanism

-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