Really, everything in your body plays an important role.
The most important system in the upper and lower body is the Circultory System
The metatarsals
immune system
Your hair.
Respiration
The hagoo system
it is important because your thing is cool
the nerve system is important b/c it controls all the thins in the body!!!!!!!
The reproductive system. All the others have a function important to the body; all the reproductive system does is... well, allow you to procreate, and make you look either masculine or feminine. Without a reproductive system, you'd look weird, but nothing else.
It's the system that helps carry oxygen into our body's and we need oxygen in our body
its transports nutrients to the body and take waste out