My 3yo is a bit anatomy obsessed too! I got a model of the human body (female) and did all of the painting and gluing for her. Then I let her place the body parts using the instruction guide and pictures from a kids anatomy book we have.

I also bought her the My First Human Body coloring book (3.99 at Barnes and Noble).

I'm in the process right now of trying to find kid friendly anatomy videos on youtube, but so far I'm not having much luck.