One very important buffer solution is human blood! An equilibrium between carbonic acid (H₂CO₃) and its conjugate base bicarbonate (HCO₃⁻) helps blood to maintain a relatively constant pH of around 7.4. The carbonic acid buffer system is created by carbon dioxide (CO₂) dissolved in blood; carbon dioxide reacts with water (H₂O) to form carbonic acid. Since the amount of carbon dioxide in the blood depends on the rate at which you breathe, your blood pH is influenced by your breathing rate. Your body can actually tell when your blood pH gets too high or too low and adjusts your respiratory rate accordingly!