8 Questions
Where is alcohol primarily metabolized?
Liver
What is the primary factor that determines the effects of alcohol?
The concentration of alcohol in the blood over time
What is the byproduct produced by alcohol dehydrogenase enzyme?
Acetaldehyde
What is the reduction state of liver cells affected by?
All of the above
Which enzyme is involved in the metabolism of ethanol in non-liver tissues?
Cytochrome P450
What is the purpose of aldehyde dehydrogenase in alcohol metabolism?
To metabolize acetaldehyde to acetate
Where is aldehyde dehydrogenase present?
Mitochondria
What is required for the oxidation process of ethanol by alcohol dehydrogenase?
NAD+
Study Notes
Alcohol Metabolism
- The effects of alcohol depend on its concentration in the blood (BAC) over time.
- BAC is determined by the rates of alcohol absorption, distribution, metabolism, and excretion.
- The liver is the primary site of alcohol metabolism.
Enzymes Involved in Alcohol Metabolism
- The two main enzymes involved in alcohol metabolism are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH2).
- ADH is present in the liver cytosol and has multiple variants (isozymes).
- ALDH2 is present in the mitochondria.
Metabolism of Ethanol
- Ethanol is metabolized by ADH to produce acetaldehyde, a highly reactive and toxic byproduct.
- Acetaldehyde production can contribute to tissue damage and the addictive process.
- The metabolism of ethanol by ADH requires NAD+, which is reduced by two electrons to form NADH.
Metabolism of Acetaldehyde
- Acetaldehyde is metabolized by ALDH2 to produce acetate.
- The metabolism of acetaldehyde by ALDH2 requires NAD+, which is reduced by two electrons to form NADH.
Extrahepatic Metabolism
- Alcohol can also be metabolized in non-liver tissues, such as the brain, by enzymes like cytochrome P450 and catalase.
- These tissues do not contain ADH.
Pathological Consequences
- Chronic alcohol consumption and metabolism are linked to several pathological consequences and tissue damage.
- Tissue damage can result from the formation of reactive oxygen species (ROS) and changes in the reduction-oxidation (redox) state of liver cells.
Learn about the effects of alcohol on the body, including how it's absorbed, distributed, metabolized, and excreted, and the role of the liver in the process.
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