Diaphragm contracts to help in `"_____________"` while the contraction of abdominal muscles helps in `"_____________"`.

Answer

To solve the question, we need to fill in the blanks regarding the functions of the diaphragm and abdominal muscles during breathing.

1. **Understanding the Role of the Diaphragm**:
- The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity.
- When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity, which decreases the pressure inside the lungs.
- This process allows air to flow into the lungs, facilitating inhalation.

**Fill in the first blank (A)**: The diaphragm contracts to help in **"quiet breathing"**. Quiet breathing refers to the normal, relaxed breathing that occurs at rest.

2. **Understanding the Role of Abdominal Muscles**:
- The abdominal muscles play a crucial role during forced breathing, which is more vigorous and requires additional effort.
- When these muscles contract, they help push the diaphragm upwards and expel air from the lungs more forcefully.
- This is especially important during activities that require increased oxygen intake, such as exercise or heavy physical exertion.

**Fill in the second blank (B)**: The contraction of abdominal muscles helps in **"forced breathing"**. Forced breathing is characterized by the active effort to inhale or exhale more air than during quiet breathing.

**Final Answer**:
- Diaphragm contracts to help in **"quiet breathing"** while the contraction of abdominal muscles helps in **"forced breathing"**.

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