The affinity of haemoglobin for oxygen increases due to

Options

A. Increase of carbon dioxide in the blood and decrease in the pH
B. Increase of temperature and decrease in the partial pressure of carbon dioxide
C. Decrease in the partial pressure of carbon dioxide and rise in pH
D. Decrease of temperature and increase in partial pressure of carbon dioxide

Answer

To determine the factors that increase the affinity of hemoglobin for oxygen, we can analyze the physiological conditions affecting hemoglobin's behavior. Here’s a step-by-step breakdown of the solution:

### Step 1: Understanding Hemoglobin's Affinity for Oxygen
Hemoglobin is a protein in red blood cells that binds to oxygen. The affinity of hemoglobin for oxygen can be influenced by various factors, including pH, temperature, and the concentration of carbon dioxide (CO2).

### Step 2: Evaluating the Options
We need to evaluate the options provided to see which conditions increase the affinity of hemoglobin for oxygen.

### Step 3: Analyzing the First Option
- **Increase in Carbon Dioxide and Decrease in pH**:
- An increase in CO2 typically leads to a decrease in pH (more acidic conditions), which lowers the affinity of hemoglobin for oxygen (Bohr effect). Therefore, this option does not increase affinity.

### Step 4: Analyzing the Second Option
- **Increase of Temperature and Decrease in Partial Pressure of CO2**:
- An increase in temperature generally decreases the affinity of hemoglobin for oxygen. However, a decrease in the partial pressure of CO2 can increase affinity. Since one part of this option is incorrect (increase in temperature), this option does not fully support increased affinity.

### Step 5: Analyzing the Third Option
- **Decrease in Partial Pressure of CO2 and Increase in pH**:
- A decrease in CO2 partial pressure increases the affinity of hemoglobin for oxygen. Additionally, an increase in pH (more alkaline conditions) also enhances hemoglobin's affinity for oxygen. This option correctly identifies two conditions that increase affinity.

### Step 6: Analyzing the Fourth Option
- **Decrease in Temperature and Increase in Partial Pressure of CO2**:
- A decrease in temperature increases the affinity of hemoglobin for oxygen, but an increase in CO2 partial pressure decreases it. Therefore, this option is not correct.

### Conclusion
The correct answer is that the affinity of hemoglobin for oxygen increases due to a **decrease in the partial pressure of CO2 and an increase in pH**.

### Final Answer
The affinity of hemoglobin for oxygen increases due to a decrease in the partial pressure of CO2 and an increase in pH.

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