Low ph alters hemoglobin structure so that oxygen binds less strongly to hemoglobin at low po2. this increases the effectiveness of

I believe this increases the effectiveness of internal respiration. As blood nears the lungs, the carbon dioxide concentration decreases, causing the pH of the blood to increase. Increase in pH increases hemoglobin's affinity for oxygen through the Bohr effect, causing the hemoglobin to pick up oxygen entering the blood from the lungs so that it can be transported to the heart and then to the tissues.