We breathe in oxygen (O2)
Oxygenated blood travels to the heart and the rest of the body
Cells produce energy and a waste gas called carbon dioxide (CO2)
Capillaries carry deoxygenated blood
Oxygen (O2) moves from the alveoli into the blood capillaries
Carbon dioxide (CO2) moves from the capillaries into the alveoli
Carbon dioxide (CO2) is eliminated when we breathe out
3
7
2
4
5
1
6