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 defined as the amount of air that can be forcibly exhaled after the end of a normal expiration. This volume is not expelled during regular breathing but can be accessed during forceful breathing.

2. **Understanding Normal Expiration**:
- During normal breathing, a person inhales and exhales air without using maximum effort. The air that is expelled during this process is known as the tidal volume.

3. **Identifying the Air Remaining in the Lungs**:
- After a normal expiration, there is still some air left in the lungs. This air is what we refer to as the expiratory reserve volume. It represents the additional air that can be exhaled beyond the tidal volume.

4. **Measurement of ERV**:
- The expiratory reserve volume is typically measured in liters or milliliters and is part of the total lung capacity. It is an important parameter in assessing lung function.

5. **Relation to Other Lung Volumes**:
- The expiratory reserve volume is part of the functional residual capacity (FRC), which is the volume of air remaining in the lungs after a normal expiration. FRC is the sum of the expiratory reserve volume and the residual volume (the air that remains in the lungs after maximal expiration).

6. **Conclusion**:
- Therefore, the expiratory reserve volume is crucial for understanding lung capacity and function, and it indicates how much additional air can be expelled from the lungs after a normal breath.