Air rushes in through the nose and mouth and passes through the throat. Air then moves past the epiglottis which is open into the trachea.
Step 3Air moves into your bronchi. The bronchi branch out and end in tiny air sacs, called alveoli.
Step 4Air moves into your alveoli. Oxygen moves through the walls of alveoli and capillaries, entering the blood.
Step 5Carbon dioxide moves from the blood through the walls of capillaries and alveoli in order to be expelled by the lungs.
Step 6Your diaphragm moves up as it relaxes. Your ribs move inward. These movements make the space inside the chest smaller.
Step 7Your lungs are squeezed and air is pushed out of the alveoli. The air travels back through your bronchi, trachea, and nose and mouth.