## Oxygen Dissociation Curve Shifts **Key Point:** A RIGHT shift of the oxygen dissociation curve indicates DECREASED hemoglobin affinity for oxygen, meaning hemoglobin releases oxygen more readily to tissues. ### Factors Causing RIGHT Shift (Decreased O₂ Affinity) | Factor | Effect | Mechanism | |--------|--------|----------| | Increased CO₂ | RIGHT shift | Bohr effect; CO₂ + H₂O → H₂CO₃ → H⁺ | | Decreased pH (acidosis) | RIGHT shift | H⁺ ions destabilize oxy-Hb | | Increased temperature | RIGHT shift | Heat destabilizes O₂-Hb bonds | | Increased 2,3-DPG | RIGHT shift | Binds to central cavity of deoxyHb | **Mnemonic:** **CADET, face Right!** - **C**O₂ ↑ - **A**cid (H⁺) ↑ - **D**PG (2,3-DPG) ↑ - **E**xercise (heat) ↑ - **T**emperature ↑ ### Why This Matters Clinically **Clinical Pearl:** During exercise or in metabolically active tissues, CO₂ production increases, temperature rises, and pH drops locally. All these changes cause a RIGHT shift, promoting oxygen UNLOADING exactly where it is needed most. **High-Yield:** The Bohr effect (CO₂ and H⁺ effects) is the most frequently tested mechanism in NEET PG. Remember: acidosis and hypercapnia both promote oxygen release. ### Left Shift (Increased O₂ Affinity) Opposite conditions: decreased CO₂, increased pH (alkalosis), decreased temperature, decreased 2,3-DPG. This occurs in fetal blood (high Hb-F affinity) and in stored blood (2,3-DPG depletes).
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