So when we inhale, we bring in that oxygen into our blood. And when we exhale, we basically remove that carbon dioxide from our system, from our blood. Now, in number five, once we actually oxygenate this blood within the lungs, we then take that oxygen blood and we move it through the venuels and through our pulmonary vein. So we have the right pulmonary vein and the left pulmonary vein that both carry the oxygenated blood. So once again, we see that veins always carry blood to the heart but they can carry both oxygenated as well as deoxygenated blood. In this case, they bring the oxygen blood into number six, which is basically our left atrium.