We inhale many gases including oxygen but what happens to the that body use?

The body uses oxygen for cellular respiration, the process by which cells convert glucose into energy. Oxygen is transported from the lungs to the cells through the bloodstream. When oxygen reaches the cells, it is used to break down glucose and produce ATP, the energy currency of the cell.

The chemical equation for cellular respiration is:

C₆H₁₂O₆ (glucose) + 6O₂ (oxygen) -> 6CO₂ (carbon dioxide) + 6H₂O (water) + energy (ATP)

During cellular respiration, oxygen is consumed and carbon dioxide is produced. Carbon dioxide is transported from the cells to the lungs through the bloodstream and is exhaled.