Alveolar sacs, consisting of individual alveoli, increase surface area for gas exchange through elastic walls that stretch during air intake, enhancing gas exchange efficiency.
An alveolar sac is a cluster of many individual alveoli that are responsible for gas exchange. An alveolus is approximately 200 µm in diameter with elastic walls that allow the alveolus to stretch during air intake, increasing the surface area available for gas exchange. Alveoli are surrounded by thin capillaries where gases can be exchanged.
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