Why is the bicarbonate buffering system important?
The bicarbonate buffering system is important in the body because it:
- manages the acid and base imbalances produced by both normal and abnormal physiology
- assists in the handling of carbon dioxide, the waste product of cellular respiration
The equilibria involved are
CO₂ + H₂O ⇌ H₂CO₃
H₂CO₃ + H₂O ⇌ H₃O⁺+ HCO₃⁻
If there are too many hydronium ions in the blood, the H₃O⁺ will react with bicarbonate to form water and carbonic acid.
If there are too few hydronium ions in the blood, the H₂CO₃ will react to form more H₃O⁺ and HCO₃⁻.
This buffering system works with hyper- or hypoventilation to maintain plasma pH.
In the case of excess acid, hyperventilation increases the loss of CO₂ to the atmosphere. This drives the bicarbonate equilibrium to the left. Plasma acidity decreases.
Hypoventilation decreases the loss of CO₂ to the atmosphere. This drives the bicarbonate equilibrium to the right and increases the acidity.