Question

Define oxygen dissociation curve. Can you suggest any reason for its sigmoidal pattern?

Answer 1

The oxygen dissociation curve is a graphical representation of the percentage of saturation of oxyhaemoglobin at various partial pressures of oxygen.

In the lungs, the partial pressure of oxygen is high. Hence, haemoglobin binds to oxygen and forms oxyhaemoglobin. Tissues have a low oxygen concentration. Therefore, at the tissues, oxyhaemoglobin releases oxygen to form haemoglobin. The sigmoid shape of the dissociation curve is because of the binding of oxygen to haemoglobin. As the first oxygen molecule binds to haemoglobin, it increases the affinity for the second molecule of oxygen to bind. Subsequently, haemoglobin attracts more oxygen.