Dissociation of oxyhaemoglobin can be promoted by

Options

A. low
B. high `p_(CO_(2))`
C. high blood pH
D. low body temperature

Answer

To answer the question "Dissociation of oxyhaemoglobin can be promoted by?", we will analyze the factors that influence the dissociation of oxyhaemoglobin (HbO2) based on the physiological principles of gas exchange and hemoglobin's behavior.

### Step-by-Step Solution:

1. **Understanding Oxyhaemoglobin Dissociation**:
- Oxyhaemoglobin is formed when oxygen binds to hemoglobin in red blood cells. The dissociation of oxyhaemoglobin refers to the release of oxygen from hemoglobin.

2. **Factors Affecting Dissociation**:
- The dissociation of oxyhaemoglobin can be influenced by several factors, including:
- Partial pressure of oxygen (PO2)
- Partial pressure of carbon dioxide (PCO2)
- Blood pH (acidity or alkalinity)
- Body temperature

3. **Role of Carbon Dioxide**:
- An increase in the partial pressure of carbon dioxide (PCO2) in the blood promotes the dissociation of oxyhaemoglobin. This is due to the Bohr effect, where higher levels of CO2 lead to a decrease in pH (making the blood more acidic), which in turn reduces hemoglobin's affinity for oxygen.

4. **Analyzing Options**:
- **Low PCO2**: This would favor the binding of oxygen to hemoglobin, not dissociation.
- **High PCO2**: This promotes dissociation of oxyhaemoglobin, as explained above.
- **High Blood pH**: This indicates an alkaline environment, which would not promote dissociation.
- **High Body Temperature**: This can also promote dissociation, as hemoglobin releases oxygen more readily at higher temperatures.

5. **Conclusion**:
- The primary factor that promotes the dissociation of oxyhaemoglobin is **high partial pressure of carbon dioxide (PCO2)**. Therefore, the correct answer is that dissociation of oxyhaemoglobin can be promoted by high PCO2.

### Final Answer:
Dissociation of oxyhaemoglobin can be promoted by high partial pressure of carbon dioxide (PCO2).