Children have a hard time understanding how their bodies work inside because it is not something that they can see. They learn a lot -early on- by looking, touching, and smelling things. When they don’t have access to the inner workings of the human body, things within can be a mystery. As adults, we understand why things may bleed, and as long as the bleeding is minimal, we rarely freak out about it. However, to a child, blood can be something very scary indeed. The more they know about how the body works, the less they will have to fear when something minor happens to them.
I know that my daughter screams her head off when even the smallest amount of blood comes out of her body.