But within the tissue, we begin the process of unloading. So the hemoglobin, some of it dissociates the oxygen. And so now not all of it is fully saturated. So in the tissues of our body, the partial pressure of oxygen is about 40 mercury. This means that hemoglobin will unload some of that oxygen and it will move from the blood and into the tissue cells down its partial pressure concentration gradient. Partial pressure gradient.