**Question:** Methanol attacks

**Core Concept:** Methanol is an alcohol with a chemical formula of CH3OH, which can cause toxic effects when consumed. It is dangerous due to its rapid absorption and high toxicity.

**Why the Correct Answer is Right:**

Methanol toxicity results from its ability to:
1. **B. Depress central nervous system:** Methanol affects the central nervous system and impairs cognitive functions, causing confusion, visual disturbances, and ultimately, blindness.
2. **C. Inhibit oxidative decarboxylation of pyruvate:** Methanol competitively inhibits the enzyme alcohol dehydrogenase, which is responsible for converting pyruvate to acetaldehyde during the citric acid cycle. This inhibition results in increased accumulation of toxic intermediates, such as formaldehyde and formic acid.
3. **D. Form formic acid:** Methanol is converted to formic acid (formalin) upon oxidation by alcohol dehydrogenase, which can further damage tissues and organs.

**Why Each Wrong Option is Incorrect:**

A. Depress respiratory system is incorrect because methanol does not affect respiration directly. However, its toxicity can manifest as central nervous system effects, leading to respiratory depression indirectly.

**Clinical Pearl:**

**Understanding Methanol Toxicity**

Methanol toxicity is an essential concept for medical students to grasp, as it highlights the importance of distinguishing between ethanol (consumed in moderate amounts as a component of alcoholic beverages) and methanol, which is toxic and can lead to devastating outcomes.

**Correct Answer:**

Correct Answer: **B. Depress central nervous system**

Methanol toxicity primarily affects the central nervous system, leading to its devastating effects, including confusion, visual disturbances, and ultimately, blindness. Understanding this mechanism is crucial for diagnosing and treating methanol poisoning effectively.