Volume of air which cannot be measured by spirometer

Options

A. RV
B. IRV + RV
C. RV + IRV + ERV
D. TV

Answer

To solve the question regarding the volume of air that cannot be measured by a spirometer, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Function of a Spirometer**:
- A spirometer is an instrument used to measure the volume of air inhaled and exhaled by the lungs. It measures various pulmonary volumes during breathing.

2. **Identify Different Lung Volumes**:
- There are several types of lung volumes, including:
- **Tidal Volume (TV)**: The amount of air inhaled or exhaled during a normal breath.
- **Inspiratory Reserve Volume (IRV)**: The additional air that can be inhaled after a normal inspiration.
- **Expiratory Reserve Volume (ERV)**: The additional air that can be exhaled after a normal expiration.
- **Residual Volume (RV)**: The volume of air that remains in the lungs after a forceful expiration.

3. **Determine Which Volume Cannot Be Measured**:
- Among the volumes listed, the **Residual Volume (RV)** is the only volume that cannot be measured by a spirometer. This is because it represents the air that remains in the lungs even after maximal exhalation, and it cannot be expelled from the lungs to be measured.

4. **Conclusion**:
- Therefore, the volume of air that cannot be measured by a spirometer is the **Residual Volume (RV)**.

### Final Answer:
The volume of air which cannot be measured by a spirometer is the **Residual Volume (RV)**.

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