How does blood circulate through the heart?

De-oxygenated blood in the body returns to the right atrium of the heart through the superior and inferior vena cava. This blood is pumped through to the right ventricle, the tricuspid valves prevent any backflow of blood. The blood in the right ventricle is then pumped out into the lungs for oxygenation through the pulmonary artery. The pulmonary vein brings the blood back into the heart, into the left atrium. From there, the blood is pumped into the left ventricle (the last chamber of the heart). The left ventricular wall of the heart is very thick and powerful which aids it to pump the oxygenated blood (through the aorta) out of the heart and to the rest of the body.