So even from this curve we see that at a PH of 7.4, on the blue curve we see that at a 40 mmhd partial pressure we have a 70% saturation of hemoglobin. But at the same exact partial pressure inside our exercising muscles, inside our exercising tissue, at a PH of 7.2 we have a lower percent saturation, means more of the hemoglobin have unloaded that oxygen. So about 40% of the hemoglobin actually exists in its dissociated form because all that oxygen has been unloaded. And this is important because we want to ensure that the cells in our body that have a higher rate of metabolism receive that oxygen that is needed to produce ATP for the cell to actually function correctly and efficiently. Now, from this graph, we also see another important point. Notice that at a partial pressure of about 100 mercury, which is the partial pressure inside the alveoli of our lungs, our percent saturation of hemoglobin for both curves at both PH values is approximately the same.