What is the function of alveoli?

What is the function of alveoli?

• A. Gas exchange.
• B. Serve as a conduit for air.
• C. Filter inhaled particles.
• D. Produce mucus.

Answer: (A)

Alveoli are the site in the lungs where gas exchange happens. Their walls are extremely thin and wrapped in a dense network of capillaries, creating a very large surface area for diffusion. Oxygen moves from the air inside the alveoli into the blood, while carbon dioxide moves from the blood into the alveolar air to be exhaled. This exchange is facilitated by the moist lining and, in many alveoli, surfactant that keeps the walls from collapsing and allows gases to dissolve more easily. Alveoli aren’t the main air conduits—that role belongs to the trachea and bronchi—nor are they the primary site for filtering inhaled particles or producing mucus, which occur earlier in the airway and in mucus-producing cells. So, the function of alveoli is gas exchange between air and blood.

Alveoli are the site in the lungs where gas exchange happens. Their walls are extremely thin and wrapped in a dense network of capillaries, creating a very large surface area for diffusion. Oxygen moves from the air inside the alveoli into the blood, while carbon dioxide moves from the blood into the alveolar air to be exhaled. This exchange is facilitated by the moist lining and, in many alveoli, surfactant that keeps the walls from collapsing and allows gases to dissolve more easily. Alveoli aren’t the main air conduits—that role belongs to the trachea and bronchi—nor are they the primary site for filtering inhaled particles or producing mucus, which occur earlier in the airway and in mucus-producing cells. So, the function of alveoli is gas exchange between air and blood.