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
[{'content': 'Earliest change in high altitude is: \nSelect and explain. \nA. Hyperventilation, B. Decrease in work capacity, C. Drowsiness, D. Polycythemia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. HyperventilationEffect of decreased Barometric pressure due to increasing (high)altitude Lead to PO2 a. At 3000m (10,000 feet) -- Po is 60mmHg (above the sea level) Hypoxic stimulation of chemo receptors es ventilation (Hyper ventilation) of all in arterial PCO2 --Respiratory alkalosisb. Acute Hypoxic symptoms -Acute mountain sickness in unacclimatized persons: -i. At 3700m (12000 feet) symptoms: irritability, drowsiness, lassitude, mental and muscle fatigue.ii. Above 18,000 feet seizuresiii. Above 23,000 feet (consciousness lost)c. Delayed effects of high altitude -This syndrome develops 8-24 hours after arrival and last 4-8 days. It is C/B: -i. Headache, irritability, insomnia, breathlessness and nausea and vomiting.ii. Cause cerebral edema due to arteriolar dilationiii. T/t for Alkalosis Acetazolamide and for cerebral edema gluco-corticoidsiv. High altitude pulmonary edema is a serious form of mountain sickness pulmonary edema', 'role': 'assistant'}]