Under which of the following condition, the oxyhaemoglobin dissociation curve shifts to left ?

Options

A. High temperature
B. High `pCO_(2)`
C. Increase in pH
D. Decrease in pH

Answer

To determine the conditions under which the oxyhemoglobin dissociation curve shifts to the left, we need to understand the factors that influence this curve. The oxyhemoglobin dissociation curve illustrates the relationship between the saturation of hemoglobin with oxygen and the partial pressure of oxygen (pO2) in the blood.

### Step-by-Step Solution:

1. **Understanding the Oxyhemoglobin Dissociation Curve**:
- The curve represents how readily hemoglobin binds to oxygen at various pO2 levels.
- A leftward shift indicates that hemoglobin has a higher affinity for oxygen, meaning it binds oxygen more tightly.

2. **Factors Affecting the Curve**:
- The curve can shift to the right or left based on certain physiological conditions.
- A right shift indicates a decreased affinity for oxygen, while a left shift indicates an increased affinity.

3. **Conditions Leading to a Left Shift**:
- **Decreased CO2 Levels**: Lower levels of carbon dioxide in the blood lead to a leftward shift.
- **Decreased Temperature**: A cooler temperature also contributes to a higher affinity for oxygen, thus shifting the curve to the left.
- **Increased pH**: A higher pH (more alkaline conditions) results in a leftward shift, meaning hemoglobin holds onto oxygen more tightly.

4. **Analyzing the Options**:
- If we are given multiple-choice options, we need to identify which of them corresponds to the conditions that cause a leftward shift.
- For example, if the options include high temperature, high pCO2, increased pH, and decreased pH, we can analyze them:
- High Temperature: Right shift
- High pCO2: Right shift
- Increased pH: Left shift (this is the correct answer)
- Decreased pH: Right shift

5. **Conclusion**:
- The condition that causes the oxyhemoglobin dissociation curve to shift to the left is **increased pH**.