of the respiratory system:
For the cells
to get oxygen, the following functions need to be accomplished:
Oxygen needs to move from the lungs
into the blood.
Air needs to be pulled from the atmosphere
into the lungs.
Air needs to have a passage through
which it can move into the body.
Breathing needs to be controlled (such
that the body can get the amount of oxygen it requires).
Organs of respiration have to be protected