DD is nearly 6. She is constantly bombarding me with questions (as they do at that age). Normally I look up google to answer them. Lately she has been asking a lot of body related questions about why our arms and legs move, why do we wee and poo and about skulls and brains. They are not doing this in school as this term's science topic is planets, moon and stars. Now I can answer these body questions without google but not at a level a 5 year old child is going to understand. I tried to explain how our arms and legs move and ended up talking about the myelin sheath and nerve impulses while DD stared at me blankly 
So does anyone know of a good book about anatomy and physiology suitable for a child? Even one aimed at a couple of years older as even if DD does not understand the explanation it would probably give me an idea at how to explain it.