The alveolus is a small, balloon like sac at the end of the small air passages in the lungs (the bronchiole). Oxygen is inhaled and absorbed into the bloodstream through the thin wall of each alveolus, and carbon dioxide is passed the other way (from the blood to the lungs) to be exhaled. There are about 300 million alveoli in each lung.
Join our Newsletter and receive our free ebook: Guide to Mastering the Study of Anatomy
We hate spam as much as you do. Unsubscribe at any time.