Question

Can you suggest any reason for the sigmoidal pattern of the oxygen dissociation curve?"

Answer 1

The sigmoidal pattern of oxygen haemoglobin dissociation curve is the result of two properties which play significant role in the transport of oxygen. These two properties are:

• Significant variations in oxygen tension occur above pO₂ of 70–80 mm Hg, whereas minimal oxygen loss from haemoglobin occurs below. A comparatively flat area of the curve represents this.
• The haemoglobin releases a disproportionately larger amount of oxygen when the partial pressure drops below 40 mm Hg. It makes the curve sigmoid and causes the steeper part of the curve to occur.