Vital capacity of lungs is

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding Vital Capacity**:
- Vital capacity (VC) is defined as the maximum amount of air that can be expelled from the lungs after maximum inhalation.

2. **Components of Vital Capacity**:
- Vital capacity is calculated by summing three specific lung volumes:
- **Inspiratory Reserve Volume (IRV)**: The amount of air that can be forcibly inhaled after a normal inhalation.
- **Expiratory Reserve Volume (ERV)**: The amount of air that can be forcibly exhaled after a normal exhalation.
- **Tidal Volume (TV)**: The amount of air that is inhaled or exhaled during normal breathing.

3. **Formula for Vital Capacity**:
- The formula for calculating vital capacity is:
\[ VC = IRV + ERV + TV \]

4. **Excluding Residual Volume**:
- Residual volume (RV) is the amount of air that remains in the lungs after a forced exhalation and is not included in the vital capacity calculation.

5. **Conclusion**:
- Based on the components and the formula, the correct answer to the question "Vital capacity of lungs is" is:
- **Inspiratory reserve volume plus expiratory reserve volume plus tidal volume**.

**Final Answer**:
- The correct option is **B**: Inspiratory reserve volume plus expiratory reserve volume plus tidal volume.

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