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. So the flat curve tells us that even if the partial pressure in the Alveoloi drops, hemoglobin will still be pretty much saturated. Now, let's move on to point number two. Now, within our tissues, if our tissues aren't active, if we're not actively exercising, then our partial pressure of oxygen inside the tissues, on average, is about 40 mercury.