Oxygen transport

• Oxyhaemoglobin dissociation curve:

  • Oxygen is loaded in regions with a high partial pressure of oxygen (e.g alveoli)

  
• Oxyhaemoglobin dissociation curve:

  • Oxygen is unloaded in regions of low partial pressure of oxygen (e.g respiring tissues)

  
• • The curve shows a steep section in the middle where it is easy for oxygen to bind as po2 increases
  • But shows shallow gradients at low and high pO2 where it is harder for oxygen to bind

  
• The curve shows that where pO2 is high (eg lungs) haemoglobin has a higher affinity for oxygen, so it will have a higher oxygen saturation

  
• At low pO2 (eg respiring tissues during exercise), haemoglobin has a low affinity for oxygen, so it has a low saturation of oxygen

  
• • 100% oxygen saturation means every haemoglobin is carrying four oxygens
  • 0% oxygen saturation means no haemoglobin molecules have any oxygen bound

  
• Saturation of haemoglobin with oxygen - When haemoglobin is holding the maximum amount of oxygen it can bind
• Cooperative binding:

  • The cooperative nature of oxygen binding to haemoglobin is due to the haemoglobin changing shape when the first oxygen binds
  • This then makes it easier for further oxygens to bind
• The further to the left the curve, the greater is the affinity of haemoglobin for oxygen (loads oxygen readily but unloads it less easily)
• The further to the right the curve, the lower is the affinity of haemoglobin for oxygen (loads oxygen less readily but unloads it more easily)