When the theory that the sun goes around earth was replaced with the theory that earth goes around the sun, this was an example of a

That's usually called the Earth's "orbit", although the word simply means the path of any object through space under the influence of gravity, even if that object isn't circling another one. Its an example of a paradigm shift .

Excretory system is important to the proper functioning of the body as it removes all the waste materials, which if accumulated, can be toxic for the body. for instance, high levels of urea in blood can be hazardous for cells of the body. when the excretory system does not work well, it can lead to several diseases including kidney stones, nephritis, cystitis, etc.