Answer: Through the tricuspid valve, the heart moves oxygen-poor blood from the right atrium to the right ventricle. The blood is subsequently pumped by the right ventricle down the pulmonary artery to the lungs, where it enters the respiration process to absorb oxygen and expel carbon dioxide. The oxygen-rich blood then travels through the pulmonary veins back to the left atrium of the heart. Through the mitral valve, the left atrium delivers blood that is oxygenated to the left ventricle. The aorta, which divides into smaller arteries that carry blood to numerous organs and tissues, is how the left ventricle subsequently pumps the oxygen-rich blood to the rest of the body.