How the Body Maintains its Acidity and Alkalinity Maintaining Blood Ph Acidity and Alkalinity

In order for the body to function normally, the maintenance of the acidity and alkalinity of the body is vital.  The normal pH of blood is 7.35 to 7.45 with an average of 7.4.  This slightly alkaline blood ph must be maintained to avoid detrimental effects like comma and evident death.  How the body maintains its acidity and alkalinity is a complex process.  Presented here is a simple outline regarding the complex process.

Organs involved

The organs involved in the maintenance of blood pH are the lungs and the kidneys.  The lungs exhale carbon dioxide to help with pH control while the kidneys excrete hydrogen ions and bicarbonates according to the needs of the body. 

Substances involved

Carbon dioxide and hydrogen are considered acidic substances they are excreted more when the body is too acidic. Bicarbonate is considered an alkaline substance so it is excreted more when the body is too alkaline.

Processes that occurs

How the body maintains its acidity and alkalinity is based on the processes that occur in the kidneys and the lungs.


When the kidneys are dysfunctional and could not respond to the imbalance in blood pH, the lungs will respond.  People hyperventilate to bring out more carbon dioxide, an acidic substance, thereby decreasing the acidity of the blood.  When there is alkalosis, hypoventilation occurs to retain more carbon dioxide hence, making the blood more acidic.

Bicarbonate excretion by the kidneys

If the lungs are dysfunctional, the kidneys will respond by increasing or decreasing the excretion of bicarbonate and hydrogen ions.   When the body is acidotic or has the condition acidosis, the kidneys will excrete more hydrogen ions and retain more bicarbonate to return the blood pH to normal. When the body is alkaloid, the kidneys will increase the excretion of bicarbonate and decrease the excretion of hydrogen ions. Through these processes, the blood pH is maintained.

Acid-base buffer system in the body

The formation of carbonic acid and bicarbonate is reversible so when the body needs more alkalinity, bicarbonate is formed. If the body needs more acidity, carbonic acid is formed. 

Homeostasis is maintained through these processes and normal blood pH is restored. In cases where both the lungs and the kidneys are dysfunctional then medical intervention is needed and appropriate medication or management is given to the patient.

Knowing how the body maintains its acidity and alkalinity is good because you will understand why at times you hyperventilate even when you do not want to.