Expiratory capacity is

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding Expiratory Capacity:**
- Expiratory capacity refers to the maximum volume of air that can be exhaled after a normal inspiration. It is a measure of lung function.

2. **Components of Expiratory Capacity:**
- Expiratory capacity is calculated as the sum of two specific lung volumes:
- **Tidal Volume (TV):** This is the amount of air that is inhaled or exhaled during a normal breath.
- **Expiratory Reserve Volume (ERV):** This is the additional amount of air that can be forcibly exhaled after the expiration of a normal tidal volume.

3. **Formula for Expiratory Capacity:**
- The formula for expiratory capacity can be expressed as:
\[ \text{Expiratory Capacity} = \text{Tidal Volume (TV)} + \text{Expiratory Reserve Volume (ERV)} \]

4. **Evaluating the Options:**
- Now, we will evaluate the provided options to identify which one correctly defines expiratory capacity:
1. **Option 1:** Tidal Volume + Expiratory Reserve Volume (Correct)
2. **Option 2:** Tidal Volume + Inspiratory Reserve Volume (Incorrect, this is Inspiratory Capacity)
3. **Option 3:** Vital Capacity + Residual Volume (Incorrect, this equals Total Lung Capacity)
4. **Option 4:** Expiratory Reserve Volume + Expiratory Reserve Volume + Tidal Volume (Incorrect, this is not a standard definition)

5. **Conclusion:**
- The correct answer is **Option 1: Tidal Volume + Expiratory Reserve Volume**, which accurately represents the definition of expiratory capacity.

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