What would happen if human blood becomes acidic ( low pH) ?

Options

A. WBC count increases
B. RBC count decreases
C. oxygen carrying capacity of haemoglobin increases
D. oxygen carrying capacity of haemoglobin decreases

Answer

### Step-by-Step Solution:

1. **Understanding pH and Acidity**:
- Human blood has a normal pH range of approximately 7.35 to 7.45. When blood becomes acidic, the pH drops below this range, indicating an increase in hydrogen ions (H⁺) concentration.

2. **Effect on Hemoglobin**:
- Hemoglobin is the protein in red blood cells responsible for transporting oxygen. The efficiency of hemoglobin in binding and releasing oxygen is influenced by the pH of the blood.

3. **Oxygen Dissociation Curve**:
- The oxygen dissociation curve illustrates how readily hemoglobin binds to oxygen at various partial pressures of oxygen (pO₂). The curve is typically S-shaped (sigmoid).
- As pO₂ increases, hemoglobin saturation also increases, reaching near 100% saturation at high pO₂ levels.

4. **Right Shift of the Curve**:
- When blood becomes more acidic (lower pH), the oxygen dissociation curve shifts to the right. This phenomenon is known as the Bohr effect.
- A rightward shift indicates that hemoglobin has a decreased affinity for oxygen, meaning it is more likely to release oxygen to the tissues.

5. **Factors Causing Right Shift**:
- The right shift is influenced by several factors:
- Increased partial pressure of carbon dioxide (pCO₂)
- Increased temperature
- Increased concentration of hydrogen ions (H⁺) due to low pH

6. **Consequences of Acidity**:
- As a result of the right shift, the oxygen-carrying capacity of hemoglobin decreases. This means that less oxygen is bound to hemoglobin, leading to reduced oxygen delivery to tissues.

7. **Conclusion**:
- If human blood becomes acidic (low pH), the increased concentration of H⁺ ions will lead to a rightward shift in the oxygen dissociation curve, resulting in decreased hemoglobin's affinity for oxygen and thus a reduced oxygen-carrying capacity.