The respiratory system is the body system we use to breathe in air and transport this to the rest of the body. It includes the nose and nasal cavity, pharynx, larynx, trachea, bronchi, lungs, alveoli. We breathe air in through the nose. This air is transported through the larynx to the lungs. Oxygen from the lungs is transported by the blood to the rest of our body. On its return trip, the blood carries carbon dioxide so that we can expel this as waste. :)