Gas exchange...
![Picture](/uploads/1/6/3/6/16362614/938596.png?425)
The movement of air in and out of the lungs. They inhale, and the gases move into the lungs (oxygen). Then the gases move out from the lungs (carbon dioxide). Another way is when the oxygen moves into the blood, then from the blood to the cells. While that is happening the carbon dioxide moves from the cells to the blood then from the blood to the air.