The oxygen-haemoglobin dissociation curve shifts to the right (decreased O2 affinity) with all of the following EXCEPT:
- A Increased 2,3-bisphosphoglycerate (2,3-BPG)
- B Increased CO2 (Bohr effect)
- C Decreased temperature ✓
- D Decreased pH (acidosis)
Correct answer: C. Decreased temperature
Explanation
A right shift of the O2-Hb dissociation curve means decreased Hb affinity for O2, facilitating O2 unloading to tissues. Right shift is caused by increased 2,3-BPG, increased CO2, decreased pH (acidosis), and increased temperature. Decreased temperature causes a LEFT shift — Hb binds O2 more tightly at lower temperatures, which is why hypothermia can impair O2 delivery to tissues. This is an important clinical consideration in patients undergoing cardiac surgery with induced hypothermia.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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