After forceful inspiration, the amount of air that can be breathed out by maximum forced expiration is equal to

Options

A. Inspiratory Reserve volume (IRV) `+` Expiratory Reserve Volume (ERV) `+` Tidal Volume (TV) `+` Residual Volume (RV)
B. IRV `+` RV `+` ERV
C. IRV `+` TV `+` ERV
D. TV `+` RV `+` ERV.

Answer

To solve the question regarding the amount of air that can be breathed out after forceful inspiration, we need to understand the concept of vital capacity. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Concept of Vital Capacity
Vital capacity is defined as the maximum amount of air that can be exhaled after a maximum inhalation. It is an important measure in respiratory physiology.

**Hint:** Remember that vital capacity is a combination of different lung volumes.

### Step 2: Identify the Components of Vital Capacity
Vital capacity is the sum of three specific lung volumes:
1. **Tidal Volume (TV)**: The amount of air inhaled or exhaled during normal breathing.
2. **Inspiratory Reserve Volume (IRV)**: The additional amount of air that can be inhaled after a normal inhalation.
3. **Expiratory Reserve Volume (ERV)**: The additional amount of air that can be exhaled after a normal exhalation.

**Hint:** Think of these volumes as different capacities that contribute to the total vital capacity.

### Step 3: Calculate Vital Capacity
The formula for vital capacity (VC) can be expressed as:
\[ VC = TV + IRV + ERV \]
This means that after a forceful inspiration, the total amount of air that can be exhaled (maximum forced expiration) is equal to the sum of these three volumes.

**Hint:** Make sure you understand how each volume contributes to the total capacity.

### Step 4: Conclusion
After understanding the components and their contributions, we conclude that the amount of air that can be breathed out after a forceful inspiration is indeed equal to the vital capacity, which is the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume.

**Final Answer:** The amount of air that can be breathed out by maximum forced expiration after forceful inspiration is equal to the **vital capacity**.