How does blood flow through the heart and to the body and lungs?

Blood enters the heart from the Superior and Inferior Vena Cava, which empties into the Right atrium. The tricuspid valve opens and the blood enters the right ventricle. These chambers contract forcing blood through the bicuspid valve into the left ventricle. The ventricles contract forcing the blood up the pulmonary trunk and into the pulmonary arteries which take the blood to the lungs where the blood picks up O2 and returns to the heart. The rest of the blood is pumped into the aorta and through out the body and returned to the superior and inferior vena cava via the veins.