The main way in which hemoglobin is able to help maintain the Ph of the blood is that when the concentration of H+ ions in the blood is high, the haemoglobin (containing oxygen) binds with the H+ ions until the concentration of them lowers again. The reason to why the blood could have higher than normal H+ ions could be due to exercise. When we exercise the body produces lots of CO2, this CO2 dissolves in the water in our blood to form carbonic acid. The H+ ions of the carbonic acid are absorbed by the bicarbonate solution found in haemoglobin, the bicarbonate solution is only present in haemoglobin due to the presence of oxygen inside the haemoglobin. Hemoglobin this therefore neutralizes/maintains the PH of the blood.
