Brief the Salient Features of Oxygen Dissociation Curve

Oxygen Dissociation Curve – Salient Features

  1. Shape – Sigmoid (S-shaped) due to cooperative binding of O₂ to hemoglobin.

  2. P₅₀ Value – ~26 mmHg for adult Hb (pO₂ at which Hb is 50% saturated).

  3. Physiological Range – Steep slope between pO₂ 20–60 mmHg: small pO₂ changes cause large saturation changes (important for O₂ delivery in tissues).

  4. Plateau Phase – At pO₂ > 60 mmHg (lung level), Hb remains ~90–100% saturated, ensuring loading even if pO₂ falls slightly.

  5. Shifts –

    • Right shift (↑P₅₀): ↓O₂ affinity → ↑delivery to tissues (caused by ↑temperature, ↑pCO₂, ↑2,3-BPG, ↓pH – Bohr effect).

    • Left shift (↓P₅₀): ↑O₂ affinity → less delivery (caused by fetal Hb, ↓temperature, ↓pCO₂, ↓2,3-BPG, ↑pH).

Short Answer:

Oxygen Dissociation Curve:
It is S-shaped showing hemoglobin’s cooperative binding to oxygen, with P₅₀ ~26 mmHg.
Right shift → ↑O₂ release (↑CO₂, ↑temp, ↓pH); Left shift → ↑O₂ affinity (↓CO₂, ↓temp, ↑pH).