Oxygen carbon oxide. Yep. That's called gas transport. Then you've got the what's called internal respiration, where you exchange gases from the blood to the tissues and vice versa. And that process is the same process as what we just spoke about at the LVRI in New York. The gases just move down their own concentration gradient. In an opposite way. For example, in the blood, the oxygen's 100 millimeters of mercury, but at the tissues, it's 40. So it goes down that hill from blood to tissue.