<prompt> Natural acclimatization in high altitude is due toIncreased ventilationIncreased oxygen utilizationIncrease the chest size and decrease the abdominal circumferenceaccommodateDecreased oxygen level  <response>: Decreased oxygen level: 650-Ganong-24th edition, 488-89- A.KJain 5th, 529-30- Guyton 12th Hypoxia in permanent residents at high altitude is called acclimatization at high altitude MechanismArterial pO2Stimulate peripheral chemoreceptorsPulmonary ventilationCO2 washoutl Alveolar pCO2H concentration in blood Alkalosis and this should inhibit the respiration Differences between High Altitude Native and Newcomer to High Altitude1. Increase in pulmonary ventilationMore thereforea Chest become enlarged barrel shapeb Alveolar ventilation is morec FRC is moreLess thereforea Chest is smaller in sizeb Alveolar ventilation is lessc FRC is less2. Response to hypoxic stimulationMore, therefore, hypocapenic alkalosis is lessLess3. Urine reactionAlkalineAcidic4. Affinity of haemoglobin for O2Less, therefore, more O2 is released from haemoglobinMore , therefore body tissue suffers from hypoxia,5. RBC countHigher, therefore PCV increases,Because of polycythemia, these individuals have red cheeksLow6. Organ vascularityMoreLess7. Mitochondria and myoglobin content of muscleHighLow8. Diffusion capacity of lung for O2MoreLess 