Why does the respiratory system require two organ systems

The lungs expel the carbon dioxide and bring in new oxygen-containing air. Only when both systems are working together can oxygen and carbon dioxide be successfully exchanged between cells and environment. There are many other examples of this cooperation in your body. :)

I hope this was the answer :3

i won't lie i don't know so go online and ask google thats what i do

sorry to break it to ya but no one can answer your question it's just

jk but i am serious about the part that most people cant answer it beacuse you did not mention the section you are talking about. but it would if you added some detail and were a bit more specific.