This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Physiology
On acclimatizing to new height, our body maintains the body pH by 
Select and explain. 
A. Retaining HCO3, B. Excretion of HCO3 by kidney, C. Producing more Hb which is a buffer, D. Increasing 2,3-DPG
D: Increasing 2,3-DPG
Answer: D: Increasing 2,3-DPG 
Explanation: Ans: d (Increasing 2,3-DPG) Ref: Ganong 22nd ed/ p.686AcclimatizationAn acclimatized person is one who has developed compensatory mechanisms, so that hypoxia causes less adverse effects on the body.Compensatory mechanisms in acclimatization:-*Ventilatorv response:-The initial ventilatory response is small as alkalosis tends to counteract effect of hypoxia. However, ventilation increases over the next 4 days. After 4 days, ventilatory response begins to decline slowly.The respiratory alkalosis produced by hyperventilation shifts O2-Hb dissociation curve to the left, but a concomitant increase in 2,3- DPG tends to decrease the O2 affinity of haemoglobin.*Bloodresponse:-Erythropoetin secretion increases and then falls after 4 days.The increase in RBC begins in 2-3 days (polycythemia)* Compensatory changes in tissue:-Mitochondria increases in number.Myoglobin increases.Cytochrome oxidase content increases.