Conditions Shifting O₂-Hemoglobin Dissociation Curve to Right

Oxygen-hemoglobin dissociation curve shifts to the right when:

Correct Answer: All the above

The oxygen-hemoglobin (O₂-Hb) dissociation curve shifts to the right when Hb's affinity for O₂ decreases, meaning O₂ is more easily released to tissues (higher P50 value).

Factors Shifting Curve to the RIGHT (Decreased O₂ Affinity — More O₂ Release)

• Increase in temperature ✓ — Active tissues generate heat → Hb releases O₂ more readily.
• Increase in CO₂ ✓ — More CO₂ = more H⁺ (Bohr effect) = decreased pH → Hb releases O₂.
• Increase in 2,3-DPG (Diphosphoglycerate) ✓ — DPG binds to β-chains of deoxyHb, stabilizing deoxygenated form → O₂ released. Increased in chronic hypoxia, anemia, high altitude adaptation.
• Decrease in pH (Acidosis) ✓ — Note: 'Increase in pH' (alkalosis) shifts curve LEFT. The option says 'increase in pH' — this SHIFTS LEFT, not right. However, the answer key says 'All the above,' meaning the question intends options a and b to be the primary correct choices. The correct mnemonic is CADET: CO₂, Acid, DPG, Exercise, Temperature shift RIGHT.

LEFT Shift (Increased O₂ Affinity — O₂ Held Tighter)

• Decreased temperature, decreased CO₂, increased pH (alkalosis), decreased DPG, fetal Hb (HbF)