New knowledge continues to accumulate at a rapid pace. Changing technology has not only helped accelerate that process by dramatically improving the ability to uncover previously unknown facts, it has allowed new important questions to be asked. For example, molecular techniques have made it possible to decipher the genetic code for humans. This knowledge increases the ability of investigators to determine the functions of genetic code and the mechanisms that control the expression of all of its components. We are in the process of crossing the threshold of not only knowing the genetic code, but identifying how that code determines the structural and functional characteristics of humans. That knowledge will eventually produce new strategies to treat many diseases for which there is now no cure. The continuing development of electronic instruments and computing capabilities has increased the rate at which data can be collected and analyzed. New imaging systems allow investigators to view small structures, and in some cases view those structures in living animals. Continuing development of modern surgical strategies and instruments is leading to improved procedures that are less invasive than traditional treatments, and newly developed drugs improve the treatment for a variety of conditions.

A major challenge for those who teach anatomy and physiology is to help students learn basic concepts in the subject and, at the same time, help students learn how new knowledge modifies traditional concepts. The accelerating rate at which new knowledge unfolds makes it more important than ever to carefully select critical concepts and to make sure that consistency is maintained between those concepts and current knowledge from the molecular to the systemic level. It is equally important to present these concepts in a way that helps students comprehend the information and teaches them to utilize their knowledge of anatomy and physiology to predict how systems will respond to changing activity, changing environmental conditions, and to trauma and disease.

Despite changing teaching and learning styles and the continuous influx of new information in the field, the principles upon which Anatomy and Physiology was founded over twenty years ago still hold true today. Since its inception, this text has been designed to help students develop a solid, basic understanding of anatomy and physiology without an encyclopedic presentation of detail. Great care has been taken to select important concepts and to carefully develop explanations of those concepts in a systematic way. The recipe we have followed for seven editions combines clear and accurate descriptions of anatomy, precise explanations of how structures function, and examples of how they work together to maintain life.

These key ingredients are seasoned with careful examples that illustrate the basic concepts of anatomy and physiology in a familiar context. Explanations of how the systems respond to aging, to changes in physical activity, to injury, and to disease—with a special focus on homeostasis and the regulatory mechanisms that maintain it—clarify difficult topics by making the information accessible to students. Because the vast majority of our readers are pursuing health-related careers, numerous examples demonstrate the application of knowledge in a clinical context. For instance, enough information is presented to allow students to understand the normal structure and function of the heart and how the heart responds to age-related changes. Enough information is presented to allow students to predict the consequences of blood loss and the effects of transfusions on heart function. This information is both relevant and exciting.

To organize the massive amount of information in this textbook into a useful form, we have designed a pedagogical framework that not only helps students study and remember critical concepts, but also challenges them to synthesize the information they gain from their reading and apply it to new and practical uses. This text emphasizes critical thinking exercises, which require a working knowledge of key concepts and stimulate the development of problem-solving skills, as an important route to student success.