OXYGEN DISSOCIATION CURVE
S-shaped (sigmoidal) curve
that shows the partial pressures of oxygen (PO2)
in relation to the
Image adapted from
From the curve you can see that at high PO2, as in the pulmonary capillaries, haemoglobin is nearly 100 % saturated. This point is shown by the red arrow.
You can also see that at low PO2, as in exercising muscles, haemoglobin saturation is much lower and oxygen is released. This point is shown by the blue arrow.
The dissociation curve is sigmoidal in shape because binding of the 1st O2 molecule increases the affinity of haemoglobin for oxygen, making it easier for the next oxygen molecule to bind.
Undergraduates click here for more information on the co-operative binding of oxygen and the sigmoidal shape of the dissociation curve
Undergraduates click here for information on the effect of pH, CO2 & temperature on dissociation curves
Undergraduates click here for information on the oxygen dissociation curve for myoglobin