Well, everything is used for everything else in the body. The brain needs the gut, the gut needs the skin, the eyes need the gut, the skin needs the skeleton, and so on and so forth.
They've done studies showing that if they remove an entire intestine and cut off its vascular and nerve supply, it will continue to contract on its own. It's like the heart in that way. Of course, this doesn't occur for very long, but it does prove that the good ol' tum-tum has some of its own regulatory factors.