During physiological respiration (breathing), we breath ambient air into our lungs. Through the lungs, gases are ‘inhaled’ into the bloodstream, and ‘exhaled’ out of the bloodstream. These gases are later used in aerobic cellular respiration. This is the process by which our bodies break down nutrients into a form that the cell can use as energy. During this process glucose reacts with oxygen, forming ATP, energy that can be used by the cell. Carbon dioxide and water are created as byproducts that the blood disposes of. Nutrients and gases are needed to create this energy and maintain the cell’s proper function and life.