The pulmonary ventilation frequency (number of inhalations per time unit) rises or lowers the carbon dioxide concentration in blood. If it is intense the gas is more eliminated to the exterior and if it is reduced the gas is retained inside the organism. Applying the principles of chemical equilibriums to the formation of bicarbonate from carbon dioxide and water one gets the following: if the carbon dioxide concentration is increased the equilibrium shifts towards the formation of bicarbonate and liberation of hydrogen ions and the pH  of the solution is lowered; if the carbon dioxide concentration is lowered the equilibrium shifts reversely towards the formation of water and carbon dioxide and also of more hydrogen ions spending and the pH of the solution is raised.