Each time you breathe in, your lungs take in oxygen. Your red blood cells carry the oxygen through your body to every cell.

Your heart is your body's pumping station. It pumps your oxygen-filled blood to each part of your body with every beat, through miles of blood vessels—arteries, veins, and tiny capillaries.

Blood pressure is the force of your blood against the walls of your blood vessels. Since your heart beats about 60 times a minute, your body gets a fresh flow of oxygen-rich blood every second or so.