Book excerpt: There are many wonders in our world, but none is more wondrous than the human body. This is a textbook about that incomparable structure. It deals with two very distinct and yet interrelated sciences: anatomy and physiology. As a science, anatomy is often defined as the study of the structure of an organism and the relationships of its parts. Physiology is the study of the functions of living organisms and their parts. - p. 1.