Write the special functional activity of the following structures. For example :Kidney and `ul"excretion"`.
Alveoli and …………..

Explanation

**Step-by-Step Solution:**

1. **Identify the Structure**: The structure in question is the alveoli.

2. **Describe the Location**: Alveoli are tiny air sacs located at the end of the bronchial tubes in the lungs. There are approximately 480 million alveoli present in the lungs.

3. **Explain the Function**: The primary function of the alveoli is to facilitate gas exchange. During inhalation, the alveoli expand to take in oxygen, and during exhalation, they shrink to expel carbon dioxide.

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