Acclimatization to a high altitude is associated with which of the following changes?
Correct Answer: O2 dissociation curve shifts to right
Description: Oxygen hemoglobin dissociation curve, is the curve relating percentage saturation of the oxygen carrying power of hemoglobin to the PO2. It has a characteristic sigmoid shape due to the T-R interconversion. In deoxyhemoglobin, globin units are tightly bound in a tense (T) configuration which reduces the affinity of the molecule for oxygen. When the first oxygen is bound, the bonds holding the globin units are released, producing a relaxed (R) configuration which exposes more oxygen binding sites. Thus, binding of one oxygen molecule increases the affinity of hemoglobin to bind other O2 molecules. Ascent to high altitude triggers a substantial rise in 2,3 DPG concentration in red blood cells. Factors causing shift of the curve to right includes: Fall in pH Rise in temperature Increase in 2, 3 BPG pH of the blood falls as its CO2 content increases, so that when PCO2 rises the curve shifts to right. Ref: Textbook of Medical Physiology By Guyton, 10th Edition, Page 466 ; Ganong's Review of Medical Physiology, 23rd Edition, Page 667-9
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