Define the oxygen dissociation curve. Can you suggest any reason for its sigmoidal pattern?
The relationship between oxygen tension and its absorption by haemoglobin produces a graph called the oxygen dissociation curve. At about 100mm Hg O2 tension Hb is 98% saturated. As it falls, the saturation of Hb decreases slowly. When O2 tension is about 40 mm Hg, Oxyhaemoglobin dissociates and oxygen is available to the tissues.