The human heart has four chambers - the right atrium, left atrium, right ventricle, and left ventricle. The arteries carry oxygenated blood away from the heart while the veins carry deoxygenated blood to the heart. The aorta is the largest artery and carries oxygenated blood from the left ventricle to the rest of the body. Pulmonary veins uniquely carry oxygenated blood from the lungs to the left atrium.