How does rising CO2 affect blood pH?

How does rising CO2 affect blood pH?

• A. Increases pH by buffering with bicarbonate
• B. Raises pH through renal compensation
• C. Does not affect pH
• D. Lowers pH (acidic) via the bicarbonate buffer system, triggers increased ventilation

Answer: (D)

Rising CO2 lowers blood pH because CO2 reacts with water to form carbonic acid, which dissociates into hydrogen ions and bicarbonate. The extra H+ makes the blood more acidic, so pH drops. The bicarbonate buffer system helps resist changes, but when CO2 climbs, the net effect is an acidifying shift. In response, the body increases ventilation to blow off CO2, providing rapid respiratory compensation. Over time, renal mechanisms can adjust buffering again, but the immediate consequence of higher CO2 is decreased pH and a drive to ventilate more.

Rising CO2 lowers blood pH because CO2 reacts with water to form carbonic acid, which dissociates into hydrogen ions and bicarbonate. The extra H+ makes the blood more acidic, so pH drops. The bicarbonate buffer system helps resist changes, but when CO2 climbs, the net effect is an acidifying shift. In response, the body increases ventilation to blow off CO2, providing rapid respiratory compensation. Over time, renal mechanisms can adjust buffering again, but the immediate consequence of higher CO2 is decreased pH and a drive to ventilate more.