What is the role of the alveoli in gas exchange?

The role of the alveoli in gas exchange is primarily as the site where oxygen and carbon dioxide exchange occurs. Alveoli are tiny air sacs located in the lungs that provide a large surface area for gas exchange due to their extensive network and thin walls. When you inhale, oxygen from the air fills these alveoli and diffuses across the alveolar walls into the bloodstream, where it binds to hemoglobin in red blood cells. Simultaneously, carbon dioxide, a waste product of metabolism present in the blood, diffuses from the blood into the alveoli to be exhaled. This dual exchange process is vital for maintaining the body's oxygen supply and removing carbon dioxide, which is essential for homeostasis and overall respiratory function.

The other options describe different functions or structures related to respiration and the cardiovascular system, but they do not directly pertain to the primary function of the alveoli in gas exchange. For instance, while surfactant production does occur in the alveoli and helps reduce surface tension to keep them open, it is not the main role in the context of gas exchange itself. Transport of blood pertains to the circulatory system rather than the gas exchange process within the lungs. Lastly, storage of air does not accurately reflect the function