The 6th edition of Essentials of Anatomy and Physiology is the result of extensive analysis of the text and evaluation of input from anatomy and physiology instructors who have thoroughly reviewed chapters. We are grateful to these professionals and have used their constructive comments in our continuing efforts to enhance the strengths of the book.

The effectiveness of the art has been improved in many ways in this edition. Over 100 figures have been changed. Some of the figures have been heavily revised to help students more easily understand concepts:

• The histology figures in Chapter 4 have been changed to a table format to present both descriptions and illustrations of the major tissue types found in the body together.
• Homeostasis Figures have been improved by adding a “Start Here” icon and color-coded arrows to make it easier to follow the events occurring when a variable increases or decreases. These simplified flow charts succinctly map out key homeostatic events, giving students a quick and effective summary of the mechanisms described in the text.
• A much improved illustration is Figure 7.11, which has been reorganized to better illustrate the relationship between ATP use in a muscle and the sources of ATP, such as creatine phosphate and aerobic metabolism.
• Another example is Figure 12.17, which has been changed to more clearly show the events that occur during the cardiac cycle.
• Many of the Process Figures have been fine-tuned to make them clearer and easier to follow. These figures provide well-organized, self-contained visual explanations of how physiological mechanisms work. They help students learn physiological processes by combining illustrations with parallel descriptions of the major features of each process.
• Labels of orientation have been added to various illustrations so students immediately understand what perspective they are viewing (see figure 6.19 as an example).

Numerous other figures have been changed to present more current information, achieve consistency, better coordinate with the text, or improve comprehension. Just a few additional examples include:

• Figure 17.1 is a presentation of the U.S. government’s new food pyramid correlating with new descriptions of macronutrient distribution ranges.
• Figure 18.15 from the fifth edition has been redesigned to form three separate small figures in this sixth edition.
• Micrographs were added to Figure 3.26 to further illustrate the phases of mitosis.
• Figures 13.14 and 13.15 have been redrawn to make them more consistent with the arm veins presented in figure 13.16.
• Figures 3.10 and 3.11 have also been reconfigured and relabeled for easier comparison.
• The anterior and posterior interventricular sulci of the heart have now been labeled in figure 12.5 because it makes describing the branches of the coronary arteries clearer.
• Explanatory labels were added to Figure 9.19 to aid understanding of the effect of sound waves on the structures of the ear.

Finally, some of the changes are more subtle, yet still important. We’ve adjusted leader lines, rewritten or reorganized labels, and made terminology more consistent between the text and the figures. The end result is a beautiful, accurate, up-to-date art program that has been scrutinized and approved by our peers, and supports the hallmarks of clarity, ease of comprehension, and critical thinking that this text emphasizes.

We are excited about these short real-life essays in the sixth edition. Each Case in Point reading explains how material just presented in the text can be used in understanding key anatomical and physiological concepts, especially in a clinical setting. They are designed to be interesting as well as instructional because they present information as small news-like clips taken from real life scenarios. Approximately two short Case in Point essays have been included in each chapter.

The Case in Point essays, along with Clinical Asides in each chapter, are designed to be consistent with the Predict and Critical Thinking questions. All of these elements are devised to encourage students to learn to think critically. In some cases they bring information from more than one chapter together to address sample problems and encourage more than just rote memorization.

For the sixth edition, we have kept the well-received order of topics in each chapter. Additionally, we have researched reports of new discoveries, used reviews from instructors who teach anatomy and physiology, and carefully examined the existing text to improve the text in the following ways:

• Many explanations have been made more clear
• Terminology has been made more consistent throughout the text and the illustrations
• New information applicable to the discipline has been researched and included where appropriate
• Factual data has been checked and updated or corrected if necessary
• Several explanations have been expanded to make the topics easier for students to understand
• Predict Questions and Critical Thinking Questions have been updated