This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Regulation of Respiration, Subject name: Physiology
[{'content': 'Sensitivity of central chemorecepter in COPD - \nSelect and explain. \nA. Decreased to H+, B. Increased to H+, C. Increased to PCO2, D. Increased to PO2', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e., Decreased to H+ o Primary stimulus for central chemoreceptors is an increase in hydrogen ion concentration (H) in CSF. o But, central chemoreceptors are depressed in hypoxia (COPD causes hypoxic hypoxia). "Central chemoreceptors are not stimulated by hypoxia; rather like any other cells, they are depressed by- hypoxia " ___ Priciples of medical physiology o Thus, COPD will cause depression of central chemoreceptors to other stimuli as it causes hypoxic hypoxia.', 'role': 'assistant'}]