The Carbonate/hydrogen Carbonate Buffer Is Responsible for Maintaining the PH

Short Answer

The carbonate/hydrogen carbonate buffer is responsible for maintaining the pH of human blood in a narrow range between 7.35-7.45. The following equation shows the equilibrium that exists between carbonic acid (H₂CO₃) and its conjugate base, hydrogen carbonate (HCO₃^-).
In you own words, explain what happens when a solution containing hydroxide ions is added to the system and how the buffer prevents the pH from changing.