HOW THE LUNGS AND RESPIRATORY SYSTEM WORK

You usually don't even notice it, but twelve to twenty times per minute, day after day, you breathe -- thanks to your body's respiratory system. Your lungs expand and contract, supplying life-sustaining oxygen to your body and removing from it, a waste product called carbon dioxide.

The Diaphragm's Role in Breathing

Inhalation and exhalation are the processes by which the body brings in oxygen and expels carbon dioxide. The breathing process is aided by a large dome-shaped muscle under the lungs called the diaphragm.