Likewise, when our hemoglobin is fully saturated with oxygen and one of those oxygen molecules actually dissociates, that dissociation process creates a conformational change in the hemoglobin that causes it to be more likely to dissociate the other three oxygen molecules. And this process, this type of behavior of hemoglobin, is referred to as positive. Cooperativity so the question is, what will make our hemoglobin actually release an oxygen? Well, recall that oxygen always spontaneously and naturally travels from a high concentration of oxygen to a low concentration of oxygen, from a high partial pressure of oxygen to a low partial pressure of oxygen. And we'll see that's exactly what happens when the hemoglobin actually reaches the tissues and organs of our body. Now, by the way, the way that we designate partial pressure of oxygen is p two, where P is the partial pressure and two is our oxygen.