How do nails grow and which organ is the largest in the body? How much blood does the heart pump and what is that blood made of? With so many systems working together to keep us alive, readers may have a lot of questions about how their body works! In this book, readers discover not only the answers to some of their toughest questions, but answers to things they may not have thought to ask before. Diagrams and full-color illustrations reinforce the main content.