Cardiovascular System

You have about 6 to 9 liters of blood in your body depending on body size. Your resting heart rate and breathing rate... is your resting heart and breathing rate, about 70 beats/min. At rest most of this blood is in the veins throughout your body, not within your arteries or within your lungs. This is because the journey of blood through your body's veins takes longer than that through your arteries or lungs.
During exercise, however, the time needed for the journey of blood through these tiny vein passageways (billions of canals) is lessened. This is because during exercise blood flowing…