How does blood circulate through the heart?

The unoxygenated blood enters through the inferior and superior vena-cava, flows into the right atrium, then to the right ventricle. After that it goes to the lungs through the pulmonary artery and comes back through the right and left pulmonary veins into the left atrium. It then goes to the left ventricle and to the aorta where it is pumped throughout the body.