Final answer:
The release of hydrogen ions from carbonic acid increases acidity and lowers the pH level; this is part of a buffer system in human blood that regulates pH, involving the binding of H+ ions to hemoglobin to limit pH shifts.
Step-by-step explanation:
When carbonic acid (H₂CO₃) releases hydrogen ions (H⁺), it dissociates into bicarbonate ions (HCO₃⁻) and H⁺. The release of hydrogen ions increases the acidity of the solution, which results in a decrease in the pH level. In the human body, this process is part of a carefully regulated buffer system involving carbonic acid and bicarbonate to maintain pH balance.
When excess H⁺ ions are produced, as can happen with increased cellular respiration during physical activity, hemoglobin can bind these ions, which helps limit shifts in pH. The CO₂/HCO₃ buffer system works to keep the blood pH at a nearly constant value by changing the total concentrations of its components.