What are alveolar sacs primarily responsible for?

What are alveolar sacs primarily responsible for?

• A. Housing blood vessels
• B. Transferring oxygen and carbon dioxide
• C. Filtering airborne particles
• D. Producing surfactant

Answer: (B)

Alveolar sacs are primarily responsible for transferring oxygen and carbon dioxide during the process of gas exchange in the lungs. These structures are located at the end of the bronchioles and are composed of tiny air sacs called alveoli, which are surrounded by a network of capillaries. When air enters the alveoli, oxygen from the air diffuses through the thin walls of the alveoli and into the bloodstream, where it binds to hemoglobin in red blood cells. Simultaneously, carbon dioxide, which is a waste product of metabolism carried in the blood, diffuses from the blood into the alveoli to be exhaled. This critical process allows the body to take in oxygen needed for cellular functions and remove carbon dioxide, thereby maintaining the balance of gases in the bloodstream and supporting overall respiratory function.

While housing blood vessels, filtering airborne particles, and producing surfactant are important functions in the respiratory system, they do not encapsulate the primary role of alveolar sacs, which centers on the vital exchange of gases.