We have the DK Inside Guide book of the Human Body. It's pretty good. My youngest has a human body skeleton floor puzzle made of heavy foam- it's about 3 feet long. We call it, "Mister Bones" and my older dd made it a complete digestive system once, when she was about 6. She carefully made all the pieces from colored paper, cut them out, and laid them on top in proper position. I think she used the Human Body book to get things right.

have fun!