In oxygen-hemoglobin dissociation, the Bohr effect describes the rightward shift of the ODC in acidic conditions. In exercising muscle tissue, multiple factors compound this rightward shift. The correct rank order from GREATEST to LEAST contribution to rightward ODC shift in exercising muscle is:
- A CO2/H+ (Bohr) > Temperature > 2,3-DPG (during acute exercise) ✓
- B Temperature > CO2/H+ (Bohr) > 2,3-DPG
- C 2,3-DPG > CO2/H+ (Bohr) > Temperature
- D All three contribute equally during moderate exercise
Explanation
During acute exercise, the Bohr effect (CO2 and H+ accumulation in exercising muscle reducing Hb-O2 affinity) provides the most immediate and quantitatively significant rightward ODC shift, facilitating O2 unloading. Local temperature rise in active muscle (from 37°C to 40-41°C) provides an additional significant rightward shift. 2,3-DPG levels change more slowly (requiring hours of sustained exercise or hypoxia) and are not significantly altered during acute exercise bouts; their contribution is important in chronic adaptation (high altitude, anemia) but minimal acutely. Thus the rank during acute exercise is Bohr effect > temperature > 2,3-DPG changes.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.