The oxyhemoglobin dissociation curve shifts to the right in all of the following conditions EXCEPT:
- A Increase in 2,3-DPG
- B Alkalosis (pH 7.55) ✓
- C Hyperthermia (fever 39°C)
- D Hypercapnia (PaCO₂ 60 mmHg)
Correct answer: B. Alkalosis (pH 7.55)
Explanation
A rightward shift of the ODC (increased P50) reflects decreased hemoglobin–oxygen affinity, facilitating O₂ unloading in tissues. This occurs with increased H⁺ (Bohr effect), elevated CO₂, hyperthermia, and increased 2,3-DPG. Alkalosis (decreased H⁺, increased pH) causes a leftward shift by increasing Hb-O₂ affinity, making O₂ release less efficient at tissues.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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