Why is CO poisonous for man ?

Options

A. CO effects the nerves of the lungs.
B. CO affects the diaphragm and intercostal muscles.
C. CO reacts with oxygen reducing percentage of `O_(2)` in air.
D. Hemoglobin combines with CO instead `O_(2)` and the product cannot dissociate.

Answer

### Step-by-Step Solution:

1. **Understanding Carbon Monoxide (CO)**: Carbon monoxide is a colorless, odorless gas that is produced by burning fossil fuels. It is often referred to as a silent killer because it can be lethal without warning.

2. **Hemoglobin's Role**: Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen from the lungs to the rest of the body and bringing carbon dioxide back to the lungs for exhalation.

3. **Affinity of Hemoglobin**: Hemoglobin has a higher affinity for carbon monoxide than for oxygen. Specifically, hemoglobin binds with carbon monoxide about 200 times more readily than it does with oxygen.

4. **Formation of Carboxyhemoglobin**: When carbon monoxide binds to hemoglobin, it forms a stable compound known as carboxyhemoglobin. This compound is much more stable than oxyhemoglobin (the compound formed when hemoglobin binds with oxygen).

5. **Impact on Oxygen Transport**: Because hemoglobin binds with carbon monoxide so readily, it reduces the amount of hemoglobin available to carry oxygen. This leads to a decrease in the oxygen-carrying capacity of the blood.

6. **Resulting Condition**: The reduced oxygen availability can lead to hypoxia, a condition where the body or a region of the body is deprived of adequate oxygen supply. This can result in symptoms such as headaches, dizziness, confusion, and in severe cases, it can be fatal.

7. **Conclusion**: Therefore, carbon monoxide is poisonous to humans because it binds to hemoglobin more effectively than oxygen, forming a stable compound that prevents the transport of oxygen in the blood.