Simulation · Biology · Class 11
The oxygen dissociation curve
From the lesson Transport of oxygen in Breathing and Exchange of Gases. Change the values and watch what happens.
The idea behind it
NCERT §14.4, §14.4.1
- Blood carries O₂ and CO₂. About 97 per cent of O₂ travels bound to haemoglobin in RBCs; the remaining 3 per cent is dissolved in plasma.
- Haemoglobin is a red, iron-containing pigment in RBCs. O₂ binds it reversibly to form oxyhaemoglobin, and each haemoglobin molecule can carry at most four molecules of O₂.
- Binding of O₂ depends mainly on pO₂; pCO₂, hydrogen ion concentration and temperature also affect it.
- Plotting percentage saturation of haemoglobin against pO₂ gives a sigmoid curve, the oxygen dissociation curve, which is very useful for studying how pCO₂, H⁺ concentration and other factors affect O₂ binding.
- In the alveoli, high pO₂, low pCO₂, lower H⁺ concentration and lower temperature all favour formation of oxyhaemoglobin.
- In the tissues, low pO₂, high pCO₂, higher H⁺ concentration and higher temperature favour dissociation of O₂ from oxyhaemoglobin.
- Under normal physiological conditions, every 100 mL of oxygenated blood delivers around 5 mL of O₂ to the tissues.