I'm having trouble understanding the chemistry behind the bicarbonate buffer system. I understand it's real world applications fine enough (Blood acidity, pH, signs and symptoms of resp/met acidosis/alkalosis, interpretation of blood gasses, etc.), I just don't understand the chemistry.

Ok, so you have the equation:

C02 + H20 <> H2C03 <> H+ + HC03-

I also understand Le Chatelier's principle which explains how equations adjust to changes to create new equilibrium.

My question is, if C02 indirectly creates more Hydrogen ion AND Bicarbonate, why is there any change of the pH at all? We always think of C02 as an acid and Bicarb as a base, but if C02 indirectly creates both an acid and a base, wouldn't this have no net change in pH? Something isn't adding up in my mind.