What is the effect of an increase in carbon dioxide on the oxygen dissociation curve?

What is the effect of an increase in carbon dioxide on the oxygen dissociation curve?

• A. Shifts left
• B. No change
• C. Increases affinity
• D. Shifts right due to carbaminohemoglobin and increased H+

Answer: (D)

An increase in carbon dioxide lowers blood pH and promotes formation of carbaminohemoglobin, both of which reduce hemoglobin’s affinity for oxygen. This is the Bohr effect in action: more H+ binds to hemoglobin, stabilizing the deoxygenated form and making it easier to release O2 to tissues. CO2 itself also binds to hemoglobin at amino groups to form carbaminohemoglobin, further decreasing O2 affinity. The combined effect is a rightward shift of the oxygen dissociation curve, meaning higher P50 and enhanced oxygen unloading where CO2 is high. In the lungs, CO2 is expelled and pH rises, shifting the curve back to the left to promote oxygen uptake.

An increase in carbon dioxide lowers blood pH and promotes formation of carbaminohemoglobin, both of which reduce hemoglobin’s affinity for oxygen. This is the Bohr effect in action: more H+ binds to hemoglobin, stabilizing the deoxygenated form and making it easier to release O2 to tissues. CO2 itself also binds to hemoglobin at amino groups to form carbaminohemoglobin, further decreasing O2 affinity. The combined effect is a rightward shift of the oxygen dissociation curve, meaning higher P50 and enhanced oxygen unloading where CO2 is high. In the lungs, CO2 is expelled and pH rises, shifting the curve back to the left to promote oxygen uptake.