what is vital capacity of our lungs

Options

A. total lung capacity minus residual volume
B. inspiratory reserve volume plus tidal volume
C. total lung capacity minus expiratory resrerve volume
D. inspiratory reserve volume plus expiratory reserve volume plus tidal volume

Answer

**Step-by-Step Solution:**

1. **Understanding Vital Capacity**:
- Vital capacity is defined as the maximum volume of air that can be expelled from the lungs after a maximum inhalation. This means it measures the amount of air a person can exhale forcefully after taking the deepest breath possible.

2. **Components of Vital Capacity**:
- Vital capacity is made up of three components:
- **Inspiratory Reserve Volume (IRV)**: The maximum amount of air that can be inhaled after a normal inhalation.
- **Tidal Volume (TV)**: The amount of air inhaled or exhaled during normal breathing.
- **Expiratory Reserve Volume (ERV)**: The maximum amount of air that can be exhaled after a normal exhalation.

3. **Formula for Vital Capacity**:
- The formula for calculating vital capacity is:
\[ \text{Vital Capacity} = \text{Inspiratory Reserve Volume} + \text{Tidal Volume} + \text{Expiratory Reserve Volume} \]

4. **Typical Values**:
- In a healthy adult, the vital capacity typically ranges from 4 to 5 liters.

5. **Measurement**:
- Vital capacity can be measured using a device called a spirometer, which assesses lung function by measuring the volume of air inhaled and exhaled.

6. **Identifying the Correct Option**:
- Given the options in the question:
- Total lung capacity minus residual volume (Incorrect)
- Inspiratory reserve volume plus tidal volume (Incorrect)
- Total lung capacity minus expiratory reserve volume (Incorrect)
- Inspiratory reserve volume plus expiratory reserve volume plus tidal volume (Correct)
- The correct answer is the last option, which accurately represents the definition of vital capacity.

**Final Answer**: The vital capacity of our lungs is the sum of the inspiratory reserve volume, tidal volume, and expiratory reserve volume.

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