Answer to Question #4022 in Physical Chemistry for Colleen

Question

Blood receives an excess of carbon dioxide from matabolic activities, which slightly lowers blood pH, yet the blood remains relatively constant. Explain how CO2 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 wook 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.