Residual volume is

Options

A. lesser than tidal volume
B. greater than inspiratory volume
C. greater than vital capacity
D. greater than tidal volume

Answer

**Step-by-Step Solution:**

1. **Understanding Residual Volume (RV):**
- Residual volume is defined as the amount of air that remains in a person's lungs after a complete exhalation. This volume is crucial as it prevents the lungs from collapsing and keeps the alveoli expanded.

2. **Measurement of Residual Volume:**
- The typical value for residual volume in a healthy adult is approximately 1200 ml. This volume cannot be expelled even after maximal expiration.

3. **Comparison with Other Lung Volumes:**
- **Tidal Volume (TV):** This is the amount of air that moves in or out of the lungs with each respiratory cycle, which is about 500 ml in a healthy male adult.
- **Inspiratory Reserve Volume (IRV):** This is the amount of air a person can inhale forcefully after a normal tidal volume inspiration, approximately 3000 ml in males and 2100 ml in females.
- **Vital Capacity (VC):** This is the total amount of air exhaled after maximum inhalation, which includes tidal volume, inspiratory reserve volume, and expiratory reserve volume.

4. **Analyzing the Relationships:**
- Residual volume (1200 ml) is less than tidal volume (500 ml), which is incorrect.
- Residual volume is not greater than inspiratory reserve volume (3000 ml).
- Residual volume is also not greater than vital capacity, which is a combination of tidal volume, inspiratory reserve volume, and expiratory reserve volume.

5. **Conclusion:**
- Therefore, the correct statement regarding residual volume is that it is greater than tidal volume.