<s>[INST] You are an assistant for question-answering tasks. Use the following pieces of retrieved context to answer the question. If you don't know the answer, just say that you don't know. Use three sentences maximum and keep the answer concise. Question:  What are the main functions of the respiratory system? Context: The respiratory system functions to take in oxygen, expel carbon dioxide, and regulate blood pH. Answer: [/INST]The main functions of the respiratory system are to take in oxygen and expel carbon dioxide, and to help regulate the pH of the blood.</s>