Steps of inhalation and exhalation.

How do the lungs take in oxygen? The steps it takes is:

• The diaphragm moves down (it is a muscle under the lungs)
• The ribs move up and out.
• This creates a low pressure system in the lungs.
• It forces air from the surrounding area into the lungs.
• The diaphragm moves up.
• The ribs move down and in.
• This creates high pressure and forces the air out.