How the Human Body Breathes
Inhaling Oxygen
The primary purpose of the respiratory
system is to bring oxygen to the lungs
and remove any unnecessary gases.
Without oxygen, mammals could not
breathe, move or turn food into energy.
All animals need oxygen to live. This is
true whether it is humans who breathe
through their mouths, fish who breathe
through their gills or reptiles who breathe through their skin. In each case, there is
an exchange of gases in the body. The respiratory system in mammals has a
passageway that goes from the mouth to the lungs for breathing. It is most
commonly called the windpipe.