what mechanisms are put in place when physiological pH falls

what mechanisms are put in place when physiological pH falls below or rises above the normal range? 12marks

Solution

Normal physiological pH of the body ranges from 7.35-7.45. If the pH value falls below 7.35, the condition is called acidosis while if the value goes above 7.45 it is known as alkalosis. In our body several acids are formed by metabolic activities like lactic avid, carbonic acid etc. These acids have to be continuously eliminated from our body to prevent build up of these acids. However rapid elimination of these acidic products can result in alkalosis while failure to eliminate the acids can lead to acidosis.

Lungs help in elimination of carbon dioxide but when more carbon dioxide is produced in the body and the lungs are not able to remove the carbon dioxide at the required amount, kidneys may help in prevention of acidosis by increasing the amount of hydrogen ions secretion into the renal fluid and reabsorption of bicarbonate ions. This way kidneys can help compensate the decreased activities of lungs to a certain degree.

Respiratory alkalosis can also result from hyperventilation of lungs. This process increases the amount of carbon dioxide release and therefore decreases the concentration of carbon dioxide in the body. As a result hydrogen and bicarbonate ions can combine to form carbonic acid which then dissociates to water and carbon dioxide. The decrease of hydrogen ions can cause the pH of the body to increase thereby causing alkalosis. Kidneys can then help in prevention of alkalosis by decreasing the release of hydrogen ions into the filtrate and also decrease the rate of reabsorption of bicarbonate ions into the blood from the flitrate.