Completar frases THE RESPIRATORY SYSTEMVersión en línea NATURAL SCIENCE. BILINGUAL SCHOOL por Gonzalo Barral 1 expelled oxygen process energy oxygen circulatory cells lungs gas dioxide cells performing carbon lungs tracts Respiration is an essential for our bodies . Through this process we receive the that our need to obtain , and expel carbon . The respiratory system is responsible for this exchange . The respiratory system consists of the respiratory and the . It works closely with the system , which transports from the lungs to the cells and dioxide from the to the , so that it can be .