Introduction to the Human Body: The Essentials of Anatomy and Physiology, Sixth Edition, is designed for courses in human anatomy and physiology or in human biology. It assumes no previous study of the human body. The successful approach of the previous editions -- to provide students with a basic understanding of the structure and functions of the human body with an emphasis on homeostasis -- has been retained. In the development of the sixth edition, we focused on improving the acknowledged strengths of the text as well as introducing several new and innovative features. - Preface.