You already know that 循環 means "circulation," so adding container makes it what holds things that circulate. They're your circulatory organs. They contain all the air moving throughout your body like a container.
Kyoko(Tokyo accent, female)
Kenichi(Tokyo accent, male)
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
There are five circulatory organ specialists in this hospital.