Answer to Question #3951 in Physical Chemistry for sharon

Question

The blood recieves an excess of carbon dioxide (CO[sub]2[/sub]) from metabolic activities which slightly lower blood pH,
yet the pH of the blood remains relatively constant. Explain how CO[sub]2[/sub] is buffered in the blood causing stabilisation of blood pH

Answer 1

In blood, CO₂ reacts with water and forms carbonic acid (H₂CO₃). This acid dissociates (to H⁺ and HCO₃^-) and can lower blood pH, but there are 4 buffering systems, that work simultaneously and prevent blood pH from changing. The systems are called bicarbonate, phosphate, haemoglobin and protein buffering systems. This systems has acceptors of protons (such as COO^- groups of proteins and haemoglobin, HCO₃^- and NaHPO₄^2-) which react with proton that is created when CO₂ dissolves in blood, so the proton is neutralized. Thus, the amount of protons is stable and blood pH does not change.