The oxygen, its partial pressure does change through the journey. It goes from 159 millimeters of mercury worth of pressure at the nose to now around about 100 in the LVRI. And carbon dioxide now, remember, when we inhaled it from the atmosphere of 0.3 millimeter of mercury in the LV RI, it's 40 millimeters of Mercury. So why is that? Well, that's because the blood that's coming to the lungs is filled with carbon dioxide and throws it out into the LVRI - so basically increasing the partial pressure of carbon dioxide in our LVRI.