Effects of co2 concentration: The Bohr effect

• Carbon dioxide partial pressure (pCO2) - The concentration of carbon dioxide in the cells
• The Bohr effect:

  • When a high carbon dioxide concentration causes the oxyhaemoglobin curve to shift to the right

  
• The Bohr effect:

  • The affinity for oxygen decreases because the acidic carbon dioxide changes the shape of haemoglobin slightly

  
• High partial pressure of Carbon Dioxide (pCO2):

  • Eg: Respiring tissues
  • Oxygen dissociates from haemoglobin more easily
  • This allows more oxygen to be unloaded to cells during intense activity
• High partial pressure of Carbon Dioxide at respiring tissues:

  • Curve shifts right
  • Decreased affinity (take up O2 less easily, but release it more easily)
  • Therefore unloads more oxygen

  
• Low partial pressure of Carbon Dioxide in the alveoli:

  • Curve shifts left
  • Increased affinity (take up O2 more easily, but release it less easily)
  • Therefore uploads more oxygen

  
• High pCO2:

  • Unloads more oxygen
  • Occurs because an increase in carbon dioxide production leads to a decrease in blood pH as it reacts with water to form carbonic acid
  • The low pH causes the quaternary structure of haemoglobin to be altered, decreasing its affinity for oxygen so increasing the dissociation of oxygen

  
• The Bohr effect - The greater the concentration of carbon dioxide, the more readily the haemoglobin releases its oxygen
• The greater the concentration of carbon dioxide, the more readily haemoglobin releases its oxygen

  • This is because dissolved carbon dioxide is acidic and the low pH causes haemoglobin to change shape