It's amazing that so few people understand the human body, especially considering that they live within it. It's perhaps the only thing you can truly say that you completely own. Many kids in school do not get an adequate education in biology, which is a travesty considering the full-importance of health care, longevity and living free from disease.
If you are one of the millions of Americans who have received less of an education on this subject than you think you need then may I please recommend an extremely valuable and easy to understand book for you?
"Human Anatomy and Physiology" by Kent M. Van de Graaff, R. Ward Rhees, Patricia Brady Wilhelm; 2001
This work boasts a crash course in biology, specifically human anatomy and physiology. The book is part of the Schaum's Easy Outline series and includes exercise questions, tips for mastering the physiology and human anatomy topic, and everything a student will need to pass a college course or final examine in the subject. The book is jam packed with information from the introduction forward.
Learn about the cell structure, tissue and cellular chemistry of the human body in the first few chapters and then the books goes on to explain the central nervous system and skeletal system, as well as the integration of the muscular components. The cardiovascular system and blood flow from the heart to the other organs. The respiratory system is completely described.