Therefore, most of the hemoglobin is saturated. Now, notice if we examine this curve, within this region of the curve, we have a relatively flat slope. Now, what exactly does that mean? Well, this flat slow basically means that even if our partial pressure inside the Alveoli dropped to below 105 mercury, most of that hemorglobin will still be fully saturated. So even if we go from, let's say, 105 to about 80 mercury inside the alveoli of the lungs, most of that hemoglobin will still be able to pick up our oxygen. And that is an important point, because in the lungs, our hemoglobin must be able to pick up that oxygen to carry it to the tissues of our body that require the oxygen.