The Heart You need your heart for all your body needs. It pumps about 2000 gallons of blood a day. It takes about 20 seconds for blood to reach every cell in the body. An artery carries blood out from the heart. A vein carries blood back to the heart. An average adult heart weighs about 10-13 ounces (300 to 350 grams). The rate which the heart pumps varies depending on what your doing. When at rest the heart pumps more slowly. When you run the heart rate increases to provide muscles and other tissues with additional oxygen they need. The typical heart rate is 72 beats per minute. Each beat gives out 2-3 ounces o