The first step in alcohol metabolism by the liver is the formation of acetaldehyde from alcohol, a chemical reaction catalyzed by:
**Core Concept**
The initial step in alcohol metabolism by the liver involves the conversion of ethanol to acetaldehyde, a process catalyzed by a specific enzyme. This reaction is crucial in understanding the pathophysiology of alcohol-induced liver damage.
**Why the Correct Answer is Right**
The correct enzyme responsible for this reaction is alcohol dehydrogenase (ADH). ADH is a cytosolic enzyme that catalyzes the oxidation of ethanol to acetaldehyde, generating NADH in the process. This reaction occurs in the cytoplasm of hepatocytes and is the primary route of alcohol metabolism in the liver. The formation of acetaldehyde is a critical step, as it is further metabolized to acetate, which can then be converted to various end products, including carbon dioxide and water.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as it does not specify a known enzyme involved in alcohol metabolism. While various enzymes are involved in the subsequent steps of alcohol metabolism, ADH is the primary enzyme responsible for the conversion of ethanol to acetaldehyde.
* **Option B:** This option is incorrect as it does not accurately represent the initial step in alcohol metabolism. While enzymes such as aldehyde dehydrogenase (ALDH) are involved in the metabolism of acetaldehyde, they are not responsible for the initial conversion of ethanol to acetaldehyde.
* **Option C:** This option is incorrect as it does not specify a known enzyme involved in alcohol metabolism. While various enzymes are involved in the metabolism of other substances, ADH is the primary enzyme responsible for the conversion of ethanol to acetaldehyde.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the first step in alcohol metabolism is catalyzed by alcohol dehydrogenase, and the subsequent steps involve the metabolism of acetaldehyde by aldehyde dehydrogenase. This understanding is crucial in managing patients with alcohol-related liver damage and in assessing the effectiveness of treatments aimed at reducing alcohol metabolism.
**Correct Answer: C. Alcohol dehydrogenase.**