A spirometer can be used to measure directly

Options

A. inspiratory capacity
B. residual volume
C. total lung capacity
D. all of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Function of a Spirometer**: A spirometer is a device used to measure the volume of air inhaled and exhaled by the lungs. It is primarily used to assess lung function and capacity.

2. **Identifying What Spirometers Measure**: Spirometers can measure various lung volumes, including tidal volume (the amount of air breathed in and out during normal breathing), inspiratory reserve volume (the additional air that can be inhaled after a normal inhalation), and expiratory reserve volume (the additional air that can be exhaled after a normal exhalation).

3. **Defining Inspiratory Capacity**: Inspiratory capacity is defined as the maximum volume of air that can be inhaled after a normal expiration. It is the sum of tidal volume and inspiratory reserve volume.

4. **Analyzing Other Lung Volumes**:
- Residual volume is the amount of air remaining in the lungs after a forceful expiration. This volume cannot be measured by a spirometer because it cannot be exhaled completely.
- Total lung capacity includes all lung volumes (tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume) and cannot be measured directly with a spirometer.

5. **Conclusion**: Based on the functions and limitations of a spirometer, it can directly measure the inspiratory capacity, which is the maximum volume of air that can be inhaled.

**Final Answer**: A spirometer can be used to measure directly the inspiratory capacity.

---