`CO_(2)` dissociates from carbamino haemoglobin when

Options

A. `PCO_(2)` is high and `PO_(2)` is low
B. `PO_(2)` is high and `PCO_(2)` is low
C. `PCO_(2)` and `PO_(2)` are equal
D. none of the above.

Explanation

To answer the question of when CO₂ dissociates from carbamino hemoglobin, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Carbamino Hemoglobin**:
- Carbamino hemoglobin is formed when carbon dioxide (CO₂) binds to hemoglobin (Hb) in the blood. This process occurs primarily in tissues where CO₂ concentration is high.

2. **Recognizing the Role of Partial Pressures**:
- The dissociation of CO₂ from carbamino hemoglobin is influenced by the partial pressures of oxygen (O₂) and carbon dioxide (CO₂).

3. **Introducing the Haldane Effect**:
- The Haldane effect describes how an increase in the partial pressure of oxygen leads to a decrease in the affinity of hemoglobin for carbon dioxide. This means that as O₂ levels rise, CO₂ is released from hemoglobin.

4. **Analyzing Conditions for Dissociation**:
- When the partial pressure of oxygen is high (such as in the lungs) and the partial pressure of carbon dioxide is low, the conditions favor the release of CO₂ from carbamino hemoglobin.

5. **Conclusion**:
- Therefore, CO₂ dissociates from carbamino hemoglobin when the partial pressure of oxygen is high and the partial pressure of carbon dioxide is low. This corresponds to option 2 in the question.

### Final Answer:
CO₂ dissociates from carbamino hemoglobin when the partial pressure of oxygen is high and the partial pressure of carbon dioxide is low.

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