What is the name of the tiny air-sacs at the end of smallest bronchioles in the lungs?

Alveoli are the tiny air sacs at the end of the smallest bronchioles in the lungs.

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Alveoli are tiny, balloon-shaped air sacs present at the very end of the respiratory tract. These are arranged in clusters throughout the lungs. The gaseous exchange takes place in the alveoli of the lungs.