All animals need oxygen to survive, without oxygen most of the organs in the body will not survive. The respiratory system helps to bring in oxygen into the body and also to remove carbon dioxide.
The respiratory system is comprised of of the nose, mouth, throat, lungs. The respiratory system helps to collect oxygen from the and then supply to the body for proper functioning.
It also helps to clean off waste products such as carbon dioxide from the body.
The respiratory system also helps in the exchange of gases in the cells that help them to function well.
Please see the link below for more information