Anatomic dead space in the respiratory tract of man is about

Options

A. 1.5 L
B. 500 mL
C. 250 mL
D. 150 ml

Answer

**Step-by-Step Solution:**

1. **Understanding Dead Space**:
- Dead space refers to the portion of each tidal volume that does not participate in gas exchange. It is important to differentiate between the two types of dead space: anatomical and physiological.

2. **Defining Anatomical Dead Space**:
- Anatomical dead space is the volume of the conducting airways, which includes the nose, mouth, trachea, and bronchi, down to the terminal bronchioles. This space is where air travels but does not engage in the exchange of gases.

3. **Volume of Anatomical Dead Space**:
- The average volume of anatomical dead space in humans is approximately 150 ml. This means that when a person inhales, this volume of air fills the conducting airways but does not contribute to oxygen and carbon dioxide exchange.

4. **Calculating the Contribution to Tidal Volume**:
- Given a normal tidal volume of about 500 ml, around 30% of this volume (which is about 150 ml) is considered dead space. This indicates that this amount of air is wasted in terms of gas exchange.

5. **Conclusion**:
- Based on the information provided, the anatomical dead space in the respiratory tract of humans is about 150 ml. Therefore, the correct answer to the question is 150 ml.

**Final Answer**: The anatomical dead space in the respiratory tract of man is about **150 ml**.

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