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What is the structural feature of alveoli?

  1. Thin-walled and balloon-like

  2. Thick-walled and tube-like

  3. Solid with no gas exchange

  4. Round and filled with liquid

The correct answer is: Thin-walled and balloon-like

The structural feature of alveoli being thin-walled and balloon-like is vital for their function in the respiratory system. Alveoli are small air sacs located at the end of the bronchioles in the lungs, and their primary role is to facilitate gas exchange. The thin walls of the alveoli, composed of a single layer of epithelial cells, allow for efficient diffusion of oxygen and carbon dioxide between the air within the alveoli and the blood in the surrounding capillaries. This structural design minimizes the distance that gases must travel, maximizing the surface area available for gas exchange. Additionally, the balloon-like shape of the alveoli helps them expand and contract during the breathing process, allowing for the intake of air and the expulsion of carbon dioxide. This unique morphology is crucial for the lungs' ability to function effectively, as it enhances both oxygen uptake and carbon dioxide removal from the body. Overall, the thin-walled and balloon-like structure of alveoli is perfectly adapted to ensure that gas exchange occurs efficiently and effectively.