First we inhale oxygen goes to the nasal cavity to the trachea to the lungs and to the heart and blood circulates oxygen and get carbon dioxide from the cells and back to the heart and the carbon dioxide will go to the lungs and we exhale it
When you inhale you get oxygen that that first enters the lungs and then into the left part of the heart.It is driven by your heart into the bloodstream,all the way through the body.The heart pumps blood which transports essential nutrients,oxygen,and other chemicals to every cell in your body.The blood delivers Carbon dioxide into the right portion of the heart,from which it is pump to the lungs.Carbon dioxide leaves your body through the lungs when you exhale.