movement of blood through the heart
There is no really start to the blood cycle, but we can start with the old blood needing to be replenished. The blood gets carried into the heart from the rest of the body that has used thought the superior and inferior vena cava. It then goes into the Right Atrium, which then pumps the blood into the right ventricle. From there the blood goes into the lungs to get replenished with oxygen. The blood then goes back to the heart and into the left atrium. It then goes down into the left ventricle and then gets pumped out to the whole body. Then when the blood gets used up it gets carried back to the heart and into the right atrium.