Mark the correct order of lung volumes

Options

A. TV `lt` ERV `lt` RV `lt` IRV
B. TV `lt` RV `lt`ERV `lt` IRV
C. IRV `lt` RV `lt`TV `lt`ERV
D. ERV `lt`TV `lt` RV `lt` IRV

Answer

To determine the correct order of lung volumes, we need to understand the definitions and approximate values of each lung volume mentioned. Here’s a step-by-step breakdown:

### Step 1: Understand Tidal Volume (TV)
- **Definition**: Tidal volume (TV) is the amount of air inhaled or exhaled during normal breathing without extra effort.
- **Approximate Value**: About 500 mL.

### Step 2: Understand Residual Volume (RV)
- **Definition**: Residual volume (RV) is the amount of air remaining in the lungs after a forced exhalation.
- **Approximate Value**: About 1.1 liters (or 1100 mL).

### Step 3: Understand Expiratory Reserve Volume (ERV)
- **Definition**: Expiratory reserve volume (ERV) is the additional amount of air that can be forcibly exhaled after the end of a normal expiration.
- **Approximate Value**: About 100 mL.

### Step 4: Understand Inspiratory Reserve Volume (IRV)
- **Definition**: Inspiratory reserve volume (IRV) is the additional amount of air that can be inhaled after a normal inhalation.
- **Approximate Value**: About 1900 mL.

### Step 5: Arrange the Lung Volumes
Now, we can arrange these lung volumes in order from the largest to the smallest based on their definitions and approximate values:
1. **Tidal Volume (TV)**: 500 mL
2. **Residual Volume (RV)**: 1100 mL
3. **Inspiratory Reserve Volume (IRV)**: 1900 mL
4. **Expiratory Reserve Volume (ERV)**: 100 mL

### Correct Order
The correct order of lung volumes from largest to smallest is:
- TV > RV > IRV > ERV

### Final Answer
The correct order of lung volumes is:
- Tidal Volume (TV) > Residual Volume (RV) > Inspiratory Reserve Volume (IRV) > Expiratory Reserve Volume (ERV).

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