3.2.2 Respiratory pH regulation Listen

Respiration also has an important regulatory function of the body’s pH. The respiratory function regulates the pH by regulating the CO2 levels in the blood.

Consider the following chemical equation:


CO2 + H2O ⇔H2CO3 ⇔ HCO3+ H+


If CO2 in the blood increases, H+ increase, because the chemical reaction will tend towards the right in such a situation. This means that the pH decreases. An increase in H+ is detected by the respiratory centre in the brain and breathing increases. An increase in ventilation results in CO2 being expired and therefore the level in the blood (the pCO2) decreases. By regulating respiration, the lungs participate in blood pH regulation by increasing or decreasing the respiration rate and the blowing out of CO2.