As the heart beats, it pumps blood through a system of blood vessels, called the circulatory system. The vessels are elastic, muscular tubes that carry blood to every part of the body.
Blood is essential. In addition to carrying fresh oxygen from the lungs and nutrients to your body's tissues, it also takes the body's waste products, including carbon dioxide, away from the tissues. This is necessary to sustain life and promote the health of all the body's tissues. Beginning with the return of blood to the heart from the systemic circulation, blood enters through the right atrium, afterwards blood flows to the right ventricle, straight through the pulmonary trunk towards the pulmonary arteries and then after to the lungs, later blood flows through the pulmonary veins, into the left atrium, then to the left ventricle and is then pumped into the aorta. Blood enters and exits the heart through the arteries. blood will then exit the right atrium through the pulmonary artery and head towards the lungs. Once blood is oxygenated by the lungs it will come back to the heart through the coronary artery and enter in the left atrium.
