Why does your chest move up and down when you breathe?

Explanation

### Step-by-Step Solution:

1. **Understanding Breathing**: Breathing is a process that involves two main actions: inhalation (taking air in) and exhalation (pushing air out).

2. **Inhalation Process**:
- When you inhale, air enters your lungs.
- As air fills the lungs, they expand and enlarge.
- This expansion causes a muscle called the diaphragm, located below the lungs, to flatten out.
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