Final answer:
The primary role of the carbonic acid−bicarbonate buffer system is to regulate the pH of the blood by absorbing excess acids or bases and preventing significant changes in pH levels.
Step-by-step explanation:
The primary role of the carbonic acid−bicarbonate buffer system is to regulate the pH of the blood. This buffer system helps maintain a stable pH by absorbing excess acids or bases and preventing significant changes in the pH levels. It involves the equilibrium between carbonic acid (H₂CO₃) and bicarbonate (HCO₃-) ions. If there is an increase in acid, bicarbonate combines with hydrogen ions to form carbonic acid, preventing a decrease in pH. Conversely, if there is an increase in base, carbonic acid dissociates to release bicarbonate and hydrogen ions, limiting the increase in pH.