Physiology, Metabolic Alkalosis

Excerpt

Normal human physiological pH is 7.35 to 7.45. A decrease in pH below this range is acidosis, an increase over this range is alkalosis. Metabolic alkalosis is defined as a disease state where the body’s pH is elevated to greater than 7.45 secondary to some metabolic process. Before going into details about pathology and this disease process, some background information about the physiological pH buffering process is important. The primary pH buffer system in the human body is the bicarbonate (HCO3)/carbon dioxide (CO2) chemical equilibrium system. Where:

1. H + HCO3 <--> H2CO3 <--> CO2 + H2O

HCO3 functions as an alkalotic substance. CO2 functions as an acidic substance. Therefore, increases in HCO3 or decreases in CO2 will make blood more alkalotic. The opposite is also true where decreases in HCO3 or an increase in CO2 will make blood more acidic. CO2 levels are physiologically regulated by the pulmonary system through respiration, whereas the HCO3 levels are regulated through the renal system with reabsorption rates. Therefore, metabolic alkalosis is an increase in serum HCO3.