Many people only know the basics about the bladder, like that it holds urine, but there's much more to learn about this extraordinary organ. For example, when empty it's only about the size of a plum, but when full it can enlarge to the size of a grapefruit. Readers of this innovative volume follow along as a friendly "body builder" shows them how the different processes and parts involved with the bladder work. Simple diagrams reinforce the understanding of key concepts. Age-appropriate text supports central aspects of the elementary science curriculum.