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CO2 effect on Oxygen-Hemoglobin Dissociation Curve

How pCO2 Affects Oxy-Hemoglobin Dissociation Curve:

  • The animations show how the concentration of carbon dioxide in the plasma (partial pressure of CO2 or pCO2) affects oxygen-hemoglobin dissociation curve (O2-Hb saturation).

CO2 effect on Oxygen-Hemoglobin Dissociation Curve

 

  • As the graphs reveal, high pCO2 has the same effect on the O2-Hb dissociation curve as low plasma pH and low pCO2 has the same effect as high plasma pH (= Bohr effect).
image descriptionHigh pCO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
High partial pressure of CO2
image descriptionLow pCO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
Low partial pressure of CO2
  • High pCO2 lessens hemoglobin’s affinity for O2 in two ways.
  • First, carbon dioxide is converted to H+ and bicarbonate ion in red blood cells via the enzyme carbonic anhydrase.

Carbon Dioxide Converted

  • The H+ ions bind to hemoglobin amino acids, and the alteration makes it more difficult for O2 to also associate.
  • Secondly, some of the carbon dioxide binds directly to hemoglobin amino acids. This also causes alteration to the hemoglobin that make it more difficult for O2 to bind.