Board Thread:Questions and Answers/@comment-23924105-20140225204908

In the very first episode Rukia said to Ichigo that she lived nearly 10 human lifetimes. While Ichigo was in the soul society he defeated Renji who then showed us a flash-back of his years as a child. During that episode we saw both him and Rukia grow from kids to adults. There are several other mentions of a soul reapers "imortality" as the anime progresses on. So what exactly are the rules that apply to soul reapers and also spirits in general? 