Which system regulates the release of bicarbonate ions to maintain pH balance in the blood?

The bicarbonate buffer system plays a crucial role in regulating the pH balance in the blood. This system involves bicarbonate ions (HCO₃⁻) and carbonic acid (H₂CO₃) in a reversible reaction that can either absorb excess hydrogen ions (H⁺) to reduce acidity or release hydrogen ions to increase acidity, thus maintaining a stable pH level.

When there are fluctuations in blood pH, the bicarbonate ions act as a base, neutralizing excess acids and preventing the blood from becoming too acidic. Conversely, when the blood pH is too high (alkaline), carbonic acid can dissociate to release hydrogen ions, helping to restore the balance. This dynamic equilibrium is critical for normal physiological functions, and the bicarbonate buffer system is the primary buffering system in the extracellular fluid, effectively ensuring that blood pH remains within the narrow range vital for proper cellular activities.

The other options refer to different buffering systems that do not primarily regulate bicarbonate ions in blood pH balance effectively. For example, the phosphate system mainly functions within the intracellular fluid and is more significant in the kidneys and bone. The protein buffer system uses amino acids and proteins but does not directly influence bicarbonate levels in the same manner