Need help with homework. Thanks!
The respritory system is just air (oxygen or O2) coming in the nose or mouth, down the pharynx then the larynx, trachea and bronchi to the alveoli.The O2 discusses through thin cell walls into the blood while carbon dioxide or CO2 diffuses into the alvoili and go out the opposite order it came in. The circulatory system... actually just here. https://www.google.com/url?sa=t&source=web&cd=1&ved=0CCoQFjAA&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCirculatory_system&ei=PPmSUbu3Hcrk4AO90IH4AQ&usg=AFQjCNFEJQe5_Ay35RVyD4G4R7PV9UCXNQ