The circulatory or cardiovascular system ensures that blood circulates into the organs and tissues of our body, carrying oxygen and nutrients and removing carbon dioxide and other waste products. Oxygen-rich blood is carried into the organs through arteries and capillaries, and once the tissues have been oxygenated, the now oxygen-depleted blood travels through capillaries, into veins and to the superior and inferior vena cava. This blood is transported to the right half of the heart and then ends up in the lungs. There, the carbon dioxide is removed from the blood and eventually exhaled. The lungs add oxygen to the blood again. The blood, now oxygen-rich once again, is transported from the lungs to the left half of the heart and pumped to the organs via the aorta.