Here's a breakdown:

* Alveoli: These are tiny air sacs in the lungs where oxygen from the inhaled air diffuses into the bloodstream, and carbon dioxide from the blood diffuses into the air to be exhaled.

* Capillaries: Tiny blood vessels that surround the alveoli, allowing for the exchange of gases.

The process of gas exchange is driven by the difference in partial pressure of oxygen and carbon dioxide between the air in the alveoli and the blood in the capillaries. This difference in pressure causes the gases to move from areas of high concentration to areas of low concentration.