Alcohol metabolism

Question 1

what are the 2 primary pathways of ethanol metabolism?

Answer 1

alcohol dehydrogenase pathway

MEOS- microsomal ethanol oxidizing system

Question 2

where is the alcohol dehydrogenase step located?

Answer 2

cytoplasm

Question 3

where is the acetylaldehyde dehydrogenase step located?

Answer 3

mitochondria

Question 4

what are the 2 steps of the alcohol dehydrogenase pathway?

Answer 4

alcohol dehydrogenase

acetylaldehyde dehydrogenase

Question 5

in the alcohol dehydrogenase pathway, the liver converts ethanol to?

Answer 5

acetylaldehyde and then to acetate

Question 6

both acetylaldehyde and acetate produce what?

Answer 6

2 NADH

Question 7

what are toxic levels of alcohol?

Answer 7

50-100mg/dl

Question 8

when alcohol dehydrogenase becomes saturated what happens?

Answer 8

we turn to the 2nd pathway MEOS

Question 9

what is the microsomal ethanol oxidizing system associated with in the cell?

Answer 9

endoplasmic reticulum

Question 10

what enzymes are associated with the MEOS?

Answer 10

cytochrome P450 system

Question 11

when ethanol converts into acetylaldehyde it requires?

Answer 11

NADPH

Question 12

In the MEOS when ethanol is converted into acetylaldehyde, what is produced and what can’t be produced?

Answer 12

free radicals are produced

NADH can not be produced

Question 13

some enzymes of MEOS are “inducible” what does this mean?

Answer 13

ethanol in high concentrations can induce the synthesis of these enzymes resulting in hepatocytes being able to metabolize ethanol more effectively

Question 14

what do we convert acetylaldehyde to acetate, what pathway is used?

Answer 14

same as ADH pathway but with acetaldehyde dehydrogenase

Question 15

acetaldehyde is 30x more toxic than ethanol and both ADH and MEOS produce it. What happens when toxicity happens

Answer 15

attaches covalently to proteins creating protein adducts; if protein is an enzyme it may be impaired

Question 16

what causes perivenular fibrosis?

Answer 16

acetaldehyde toxicity

Question 17

acetate increases acetyl CoA which increases ketogenesis which also increases

Answer 17

acidity, FA synthesis and increased acetaldehyde because ADH is inhibited

Question 18

MEOS needs NADPH but MEOS creates free radicals so NADPH can’t be used for?

Answer 18

regeneration with glutathione which leads to oxidative stress

Question 19

both alcohol metabolism pathways produce NADH, accumulation of NADH alters?

Answer 19

energy metabolism of the liver; shift toward reduction reactions

Question 20

more NADH =

Answer 20

less fat burning
more fat synthesis and TAG
Kreb’s inhibition
more lactic acid

Question 21

lipids accumulate in most tissues where ethanol is metabolized leading to?

Answer 21

fatty liver
fatty myocardium 
fatty renal tubules 
increased lipid synthesis 
decreased lipid removal

Question 22

what are the metabolic effects of alcohol metabolism?

Answer 22

krebs inhibited 
decreased fat burning 
fat accumulation 
lactate accumulation 
decreased GNG, increased ketogenesis 
decreased retinoic acid

Question 23

why does ethanol metabolism effect Vit A absorption?

Answer 23

vit A needs to be converted into retinoic acid and the same enzymes needed for this conversion are what are used for ethanol metabolism

ethanol is competitive inhibitor

Question 24

which enzyme in ethanol metabolism can become saturated?

Answer 24

alcohol dehydrogenase

Question 25

which of the steps in alcohol metabolism does not directly produce NADH?

Answer 25

MEOS