What role do alveoli play in gas exchange?

What role do alveoli play in gas exchange?

• A. They absorb oxygen only
• B. They are the site of gas exchange between air and blood
• C. They filter air before it enters the lungs
• D. They contain mucus to trap particles

Answer: (B)

Alveoli play a critical role in the respiratory system by serving as the primary site of gas exchange between the air inhaled into the lungs and the blood in the capillaries that surround them. Each alveolus is a tiny air sac that is remarkably efficient in facilitating the transfer of oxygen from the air into the blood while allowing carbon dioxide, a waste product of metabolism, to be expelled from the blood back into the air. This exchange occurs through the alveolar and capillary membranes, which are incredibly thin and provide a large surface area relative to their volume, maximizing the diffusion of gases. The oxygen that passes through the alveoli enters the bloodstream, where it binds to hemoglobin in red blood cells and is transported to tissues throughout the body. Conversely, carbon dioxide diffuses from the blood into the alveoli, from where it is expelled from the body during exhalation. Understanding this function is essential for comprehending how the human body relies on efficient respiratory mechanics to maintain adequate oxygen levels and remove carbon dioxide. The other options focus on functions that are not performed by the alveoli or are attributes associated with different structures within the respiratory system. For example, absorption of oxygen only, filtration of air, and the presence of mucus pert

Alveoli play a critical role in the respiratory system by serving as the primary site of gas exchange between the air inhaled into the lungs and the blood in the capillaries that surround them. Each alveolus is a tiny air sac that is remarkably efficient in facilitating the transfer of oxygen from the air into the blood while allowing carbon dioxide, a waste product of metabolism, to be expelled from the blood back into the air.

This exchange occurs through the alveolar and capillary membranes, which are incredibly thin and provide a large surface area relative to their volume, maximizing the diffusion of gases. The oxygen that passes through the alveoli enters the bloodstream, where it binds to hemoglobin in red blood cells and is transported to tissues throughout the body. Conversely, carbon dioxide diffuses from the blood into the alveoli, from where it is expelled from the body during exhalation. Understanding this function is essential for comprehending how the human body relies on efficient respiratory mechanics to maintain adequate oxygen levels and remove carbon dioxide.

The other options focus on functions that are not performed by the alveoli or are attributes associated with different structures within the respiratory system. For example, absorption of oxygen only, filtration of air, and the presence of mucus pert