Oxyhaemoglobin dissociation curve

• Partial pressure is the pressure that would be exerted by one of the gases in a mixture if it occupied the same volume on its own
• The partial pressure of oxygen is highest in the lungs where haemoglobin loads oxygen
• The partial pressure of oxygen is lowest in the systemic circulation where haemoglobin unloads oxygen
• Cooperativity is when the binding of oxygen to any subunits/haem group increases the likelihood that the other subunits will bind to oxygen
• The cooperativity of oxygen loading to haemoglobin influences how much of the oxygen is released from the haemoglobin and delivered to any particular tissue
• Haemoglobin saturation is the percent of haem groups binded to oxygen
• At low partial pressure, less oxygen is available to bind
• As partial pressure increases, some haemoglobin bind as positive cooperativity makes it easier for more oxygen to bind
• At high partial pressure, curve plateaus because there is a lower probability of oxygen colliding with free haem group
• Higher carbon dioxide concentration shifts the dissociation curve to the right because the affinity of haemoglobin for oxygen has decreased
• Animals with higher metabolic rate have the dissociation curve shifted to the right due to the haemoglobin having lower affinity to unload more for respiring tissue