So notice what these two curves actually tell us. At about our 40 mercury partial pressure, which is the partial pressure of oxygen inside our tissues, the value for how much of hemoglobin is actually saturated differs for these two PH. At a PH of 7.4 it's around 70% saturation and at a PH of 7.2 it's around 60% saturation of hemoglobin. So there is this difference of about 10%. And what that tells us is when our cells of the tissue are exercising and therefore producing more H plus ions and so we have a lower PH. What the lower PH means is our hemoglobin will be more likely to actually unload that oxygen into those exercising cells inside our tissue.