The blood recieves an excess of carbon dioxide (CO2) from metabolic activities which slightly lower blood pH, yet the pH of the blood remains relatively constant. Explain how CO2 is buffered in the blood causing stabilisation of blood pH
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 NaHPO42-) 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.