nitrogen - about 78%

oxygen - about 21%

argon - about 0.9%

carbon dioxide - about 0.03%

other gases - about 0.07%

Where are gases exchanged

in the lungs?

1) shaped like grapes

2) have thin walls

3) surrounded by many capillaries

4) place where oxygen and carbon dioxide are exchanged

the movement of material

from areas of high concentration 

to areas of low concentration

Inhaled air has more ___

than exhaled air.

Exhaled air has more ___

than inhaled air.

carbon dioxide

(it also has water vapor)