Wow! You've got to check this out even if you don't teach anatomy, health, or human body systems. The FREE Biodigital Human Body is a 3-D model that you can manipulate, dissect, and choose layers, systems, and organs to learn about the body, parts, systems, functions, and diseases. It is available on the web, as an app for iPad and Android, and as a Google Chrome add-on.
The images are amazing and the information is detailed enough that college students use it in their studies. As a disclaimer, you ARE viewing the human body, so be aware that ALL body systems are available (I work with elementary students, so I think about these things). There are so many ways to view the body and systems in this program that it could take awhile to learn how to use all the tools. I don't know why I haven't seen this amazing resource before!