respiration
movement of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction
en-US/ˌɹɛspəˈɹeɪʃən/
en-GB/ˌɹɛspəˈɹeɪʃn/
movement of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction