What takes place between the alveoli and capillaries in lungs?

Gas exchange.

Explanation:

The primary function of the lungs is to facilitate gas exchange between the atmosphere and the bloodstream. The alveoli, which are tiny air sacs in the lungs, are the primary sites where this exchange occurs. The alveoli are surrounded by capillaries, which are small blood vessels. As air is inhaled, oxygen from the air diffuses across the thin walls of the alveoli and into the capillaries. At the same time, carbon dioxide, a waste product of cellular metabolism, diffuses out of the capillaries and into the alveoli to be exhaled. This process ensures that oxygen-rich blood is circulated throughout the body, while carbon dioxide is removed from the bloodstream.