why does your body need oxygen
In aerobic respiration, oxygen is used within the cell to help create energy. When you breathe, air enters microscopic air sacs in your lungs called alveoli. Oxygen passes through the walls of the alveoli and into the bloodstream. The blood carries oxygen to cells throughout the body, where it helps convert nutrients into usable energy. Fun fact: oxygen is what makes your blood red. Blood without oxygen appears blue.