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': 'Sensitivity of chemoreceptors 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: C \nExplanation: The main chemoreceptors involved in respiratory feedback are: Central chemoreceptors: These are located on the ventrolateral surface of medulla oblongata and detect changes in the pH of spinal fluid. They can be desensitized over time from chronic hypoxia (oxygen deficiency) and increased carbon dioxide Ref: guyton and hall textbook of medical physiology 12 edition page number:365,366,367', 'role': 'assistant'}]