Each hemoglobin consists of four globular proteins and a heme unit forming the hemoglobin molecule. Oxygen dissolved in blood plasma binds to the iron at the center of the heme unit, each iron is capable of holding four oxygen molecules. The hemoglobin dissociation curve shows the relationship between the reaction that binds oxygen to the hemoglobin and the partial oxygen pressure in the circulatory system, the higher the pressure the more oxygen binds to hemoglobin the lower the pressure the more oxygen is released. This results in a steep raise in oxygen binding as each oxygen increases the pressure making the next reaction easier to occur. A change in temperature has a direct correlation to the dissociation curve, as temperature increases
