Key Concepts

• • Haemoglobin's sigmoidal shape enables cooperative O₂ loading and unloading
• • P₅₀: pO₂ at 50% saturation — lower P₅₀ = higher O₂ affinity
• • Bohr effect: ↑CO₂ / ↓pH shifts curve right → Hb releases O₂ more readily (promotes delivery to active tissue)
• • Myoglobin: hyperbolic curve, higher O₂ affinity than Hb — stores O₂ in muscles
• • Foetal Hb (HbF) has higher affinity than adult Hb — curve lies to the left