During expiration, diaphragm becomes

Options

A. Flattened
B. Dome-shaped
C. Oblique
D. Normal

Answer

### Step-by-Step Solution:

1. **Understanding Expiration**: Expiration is the process of breathing out air from the lungs. During this process, the diaphragm, which is a key muscle involved in respiration, plays a crucial role.

2. **Role of the Diaphragm**: The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity. Its primary function is to help in the inhalation and exhalation of air.

3. **Diaphragm during Expiration**: When we exhale, the diaphragm relaxes. This relaxation is essential for allowing air to be pushed out of the lungs.

4. **Shape of the Diaphragm**: Upon relaxation, the diaphragm returns to its original dome shape. This is because the contraction of the diaphragm during inhalation causes it to flatten, but during expiration, it relaxes and reverts to a dome shape.

5. **Conclusion**: Therefore, during expiration, the diaphragm becomes dome-shaped.

### Final Answer:
During expiration, the diaphragm becomes **dome-shaped**.

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