What role does diffusion play in respiratory function?

• A. It allows carbon dioxide to be expelled during exhalation.
• B. It ensures oxygen is transported to muscle tissues.
• C. It facilitates the exchange of gases in the alveoli.
• D. It aids in the balance of pH levels in the blood.

Answer: (C)

Diffusion is a fundamental process in respiratory function, particularly in the context of gas exchange within the alveoli of the lungs. The alveoli are tiny air sacs where oxygen from inhaled air is transferred into the blood, and carbon dioxide is removed from the blood to be exhaled. This gas exchange occurs via diffusion, which is driven by concentration gradients.

In the alveoli, oxygen concentration is higher compared to the blood in the surrounding capillaries, causing oxygen to diffuse from the alveoli into the blood. Conversely, carbon dioxide, which is in higher concentration in the blood than in the alveoli, diffuses from the blood into the alveoli to be expelled from the body during exhalation. This efficient process of gas exchange ensures that tissues receive the oxygen they require for cellular respiration while removing carbon dioxide, a metabolic waste product.

Other factors mentioned, such as the expulsion of carbon dioxide during exhalation or the transport of oxygen to muscle tissues, do involve diffusion indirectly, but they do not capture the primary role of diffusion in the context of respiratory function itself. Balancing pH levels in the blood is influenced by respiratory gases, but the immediate function of diffusion in respiration specifically relates to the exchange of gases in the