What is the expiratory reserve volume of a person ?

Options

A. TV + RV
B. FRC – RV
C. FRC – TV
D. FRC – IRV

Answer

**Step-by-Step Solution:**

1. **Definition of Expiratory Reserve Volume (ERV)**:
- Expiratory Reserve Volume is the additional amount of air that can be forcibly exhaled after the expiration of a normal tidal volume.

2. **Understanding Functional Residual Capacity (FRC)**:
- FRC is the volume of air remaining in the lungs after a normal expiration. It includes both the Expiratory Reserve Volume (ERV) and the Residual Volume (RV).
- Mathematically, FRC can be expressed as:
\[ FRC = ERV + RV \]

3. **Relationship Between ERV and FRC**:
- From the definition of FRC, we can rearrange the equation to find the Expiratory Reserve Volume:
\[ ERV = FRC - RV \]
- This means that to find the ERV, we need to know the values of FRC and RV.

4. **Conclusion**:
- Therefore, the Expiratory Reserve Volume (ERV) is the volume of air that can be forcibly exhaled after a normal tidal expiration, and it can be calculated if we have the values of FRC and RV.

**Final Answer**: The expiratory reserve volume of a person is the additional air that can be forcibly exhaled after normal expiration, which can be calculated using the formula \( ERV = FRC - RV \).

---