http://www.innerbody.com/htm/body.html

I love this site- as soon as you get to this page you start by clicking on the system you want to learn about. Say you want to learn about the digestive system- click the digestive body and it brings up a new page with the body. On the right side you have a list of all the parts of that system. Putting your pointer on the part of the body you want to learn about lights up that part of the body and clicking on it will give a description of that part of the body.