The total lung capacity is represented by

Options

A. tidal volume + vital capacity
B. tidal volume + functional residual capacity
C. vital capacity + residual volume
D. inspiratory and expiratory reserve volumes

Answer

To solve the question regarding how total lung capacity (TLC) is represented, we need to understand the components that make up TLC.

### Step-by-Step Solution:

1. **Define Total Lung Capacity (TLC)**:
- Total Lung Capacity (TLC) is the maximum amount of air that the lungs can hold. It is the sum of all lung volumes.

2. **Identify the Components of TLC**:
- TLC is composed of four main components:
- **Tidal Volume (TV)**: The amount of air inhaled or exhaled during normal breathing.
- **Inspiratory Reserve Volume (IRV)**: The additional air that can be inhaled after a normal inhalation.
- **Expiratory Reserve Volume (ERV)**: The additional air that can be exhaled after a normal exhalation.
- **Residual Volume (RV)**: The amount of air remaining in the lungs after a forced exhalation.

3. **Mathematical Representation of TLC**:
- The formula for Total Lung Capacity can be expressed as:
\[ TLC = TV + IRV + ERV + RV \]

4. **Analyze the Given Options**:
- **Option 1**: Tidal volume + Vital capacity
- Vital Capacity (VC) is defined as the maximum amount of air that can be exhaled after a maximum inhalation, which includes TV, IRV, and ERV. Thus, this option does not include RV.
- **Option 2**: Tidal volume + Functional residual capacity
- Functional Residual Capacity (FRC) is the volume of air remaining in the lungs after a normal exhalation (which includes ERV and RV). This option does not account for IRV.
- **Option 3**: Vital capacity + Residual volume
- This option includes VC (TV + IRV + ERV) and RV, thus it accounts for all components of TLC.
- **Option 4**: Inspiratory and expiratory reserve volumes
- This option does not include TV or RV, making it incomplete.

5. **Conclusion**:
- The correct representation of Total Lung Capacity is given by **Vital Capacity + Residual Volume**.

### Final Answer:
The total lung capacity is represented by **Vital Capacity + Residual Volume**.