How carbon monoxide, emitted by automobiles, prevents transport of oxygen to the body tissues?

Options

A. By destroying the heamoglobin
B. By forming a stable compound with heamoglobin
C. By obstructing the reaction of oxygen with heamoglobin
D. By changing oxygen into carbon dioxide

Answer

**Step-by-Step Text Solution:**

1. **Understanding Hemoglobin Function**: Hemoglobin is a protein in red blood cells that binds to oxygen in the lungs and transports it to tissues throughout the body. When hemoglobin binds with oxygen, it forms a complex called oxyhemoglobin.

2. **Introduction of Carbon Monoxide (CO)**: Carbon monoxide is a colorless, odorless gas emitted by automobiles and other sources. It can enter the bloodstream when inhaled.

3. **Binding of Carbon Monoxide to Hemoglobin**: Carbon monoxide has a much higher affinity for hemoglobin than oxygen does. When CO is present, it competes with oxygen for binding sites on hemoglobin.

4. **Formation of Carboxyhemoglobin**: When carbon monoxide binds to hemoglobin, it forms a stable compound known as carboxyhemoglobin. This complex is much more stable than oxyhemoglobin.

5. **Impact on Oxygen Transport**: Once hemoglobin is bound to carbon monoxide (forming carboxyhemoglobin), it cannot effectively bind to oxygen. This means that even if oxygen is present in high concentrations, hemoglobin remains occupied by carbon monoxide and cannot transport oxygen to body tissues.

6. **Conclusion**: The presence of carbon monoxide in the bloodstream prevents the transport of oxygen to body tissues by forming a stable compound with hemoglobin (carboxyhemoglobin), thereby inhibiting the normal function of hemoglobin.

**Correct Answer**: By forming a stable compound with hemoglobin (carboxyhemoglobin).

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