The respiratory system takes care of two vital functions for the body: oxygen intake during inhalation (inspiration) and carbon dioxide removal during exhalation (expiration).

Our cells need oxygen to convert nutrients from food into energy. Carbon dioxide is formed during this process and is removed during exhalation.

The lungs are the largest and most important part of the respiratory system. In the lungs, oxygen is transported to the bloodstream. Red blood cells carry oxygen to the tissues. After the oxygen is released, the red blood cells take away the carbon dioxide that is produced. Exhalation also allows for formation of sound, for example when speaking or singing.