In man, during inspiration, the dome-shaped diaphragm becomes:

Options

A. More convex anteriorly
B. More concave posteriorly
C. More or less flat
D. Contract to small size

Answer

**Step-by-Step Solution:**

1. **Understanding Inspiration**: During inspiration, the process of drawing air into the lungs occurs. This is facilitated by changes in the thoracic cavity's volume, which affects the pressure inside the lungs.

2. **Role of the Diaphragm**: The diaphragm is a dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. Its contraction is crucial for increasing the volume of the thoracic cavity during inspiration.

3. **Diaphragm Movement**: When the diaphragm contracts, it flattens out. This flattening increases the vertical dimension of the thoracic cavity, allowing more air to be drawn into the lungs.

4. **Pressure Changes**: According to the principles of gas laws, as the volume of the thoracic cavity increases (due to the diaphragm flattening), the pressure inside the lungs decreases. This pressure difference allows atmospheric air to flow into the lungs.

5. **Conclusion**: Therefore, during inspiration, the dome-shaped diaphragm becomes more or less flat, which is the correct answer to the question.

**Final Answer**: C) More or less flat.

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