Buffer in blood consists of

Options

A. `H_(2)CO_(3)` and `Cl^(-)`
B. `HCl` and `HCO_(3)^(-)`
C. `HCl` and `Cl^(-)`
D. `H_(2)CO_(3)`and `HCO_(3)^(-)`

Explanation

**Step-by-Step Solution:**

1. **Understanding Buffer Solutions:**
- A buffer solution is defined as a solution that resists changes in pH when small amounts of acid or base are added. This property is crucial for maintaining the pH of biological systems, including blood.

2. **Importance of pH in Blood:**
- The pH of blood is tightly regulated and is typically maintained at around 7.4. This is essential for proper physiological functions.

3. **Components of Blood Buffer:**
- In the blood, the primary buffer system consists of carbonic acid (H2CO3) and bicarbonate ions (HCO3⁻).
- Carbonic acid can dissociate into bicarbonate and hydrogen ions, which helps to neutralize excess acids or bases.

4. **Role of Carbon Dioxide:**
- Carbon dioxide (CO2) is also involved in the buffering system. It can react with water to form carbonic acid, thus playing a role in maintaining the balance of the buffer system.

5. **Conclusion:**
- Therefore, the buffer in the blood primarily consists of carbonic acid (H2CO3) and bicarbonate ions (HCO3⁻). Other options provided in the question (like Cl⁻) do not contribute to the buffering capacity of blood.

**Final Answer:**
The buffer in blood consists of carbonic acid (H2CO3) and bicarbonate ions (HCO3⁻).

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