Normal Breathing
This animation shows normal breathing. As we breathe in, air that contains lots of oxygen (shown in red) is pulled into the lungs. This oxygen slowly moves from the lungs into the blood. Then air that contains carbon dioxide (shown in blue) is pushed back out through the lungs as we breathe out.
When things are working normally, the amount of air we breathe in is about the same as the amount of air we breathe out.