What are the tiny air sacs in the lungs called, where gas exchange occurs?

• A. Pleura
• B. Bronchioles
• C. Alveoli
• D. Fibrils

Answer: (C)

The tiny air sacs in the lungs where gas exchange occurs are known as alveoli. These structures are essential for the respiratory process, as they provide a large surface area for oxygen to diffuse into the blood and carbon dioxide to diffuse out of the blood. The walls of the alveoli are extremely thin, which facilitates the efficient exchange of gases. Each alveolus is surrounded by a network of capillaries that transport oxygen-depleted blood to the lungs and return oxygen-rich blood to the heart.

The pleura are protective membranes surrounding the lungs and do not directly participate in gas exchange. Bronchioles are smaller air passages that lead to the alveoli but are not the sites of gas exchange themselves. Fibrils are small, thread-like structures found in a variety of tissues but are not related to respiratory function or gas exchange in the lungs. Therefore, alveoli are uniquely adapted for their role in the respiratory system, making them essential for breathing and maintaining proper oxygen levels in the body.