The exchange of gases between blood and air occurs in the alveoli of the lungs.

Here's a breakdown:

* Alveoli: These are tiny air sacs in the lungs that are surrounded by capillaries (tiny blood vessels).

* Oxygen: Oxygen from the inhaled air diffuses across the thin walls of the alveoli and into the capillaries, where it binds to red blood cells and is transported to the body's tissues.

* Carbon Dioxide: Carbon dioxide, a waste product of cellular respiration, diffuses from the blood in the capillaries into the alveoli and is then exhaled.

This exchange is made possible by the partial pressure gradients of oxygen and carbon dioxide. Oxygen has a higher partial pressure in the alveoli than in the blood, causing it to move into the blood. Carbon dioxide has a higher partial pressure in the blood than in the alveoli, causing it to move into the alveoli to be exhaled.