This 2D companion diagram lays the human body out flat, front-on, as four independent layers — skin, skeleton, muscles and organs — that you can toggle on or off just like an anatomy atlas's transparent overlay pages. Click any labeled region to see which body system it belongs to and read a short description with key facts, adjust skin opacity to peer through to the layers beneath, or jump straight to an organs-only or full-body preset. A simple heartbeat and breathing animation bring the circulatory and respiratory systems to life while you explore.