This is a fascinating and colorful look at the heart and the amazing job it performs. Computer-enhanced photos are used to illustrate the heart and the blood vessels while magnified images give us a close-up look at the blood. Also included are simpler illustrations showing the chambers of the heart, it's valves and arteries and the general make-up of arteries and veins and their valves. The text is simple enough to be understood by fairly young children (particularly as a read-aloud) but is written in such a way as to capture the awe and mystery of how our body works. It covers quite a bit of material in a fairly in-depth fashion - the basic workings and function of the heart, the various components of the blood, the various types and functions of the blood vessels, the basic path of the blood through the body, how the lungs work within the cardiovascular system, the role of white blood cells and some of the problems that people develop in their blood's circulatory system. An impressive, engaging and informative book.