Preface

This 9th edition of Hole represents our third revision as an author team. Since the seventh edition we have been trying to carry John Hole's work forward, bringing the content and context in synch with the ever-changing field of A&P and taking full advantage of current technologies in developing our ancillary offerings.

In a way, the third time has been the charm. It is not surprising in retrospect that we would not feel a sense of ownership until now. John Hole's text was well established, and as a new author team we were successful in updating and upgrading the content and presentation of the 7th and 8th editions without changing the accessibility and readability that made the book the success that it has been. However the constraints of taking over someone else's work are inescapable, and looking back, we did not make changes that we could have because they were not necessary. And we did not take liberties we might have because we did not feel free to do so.

The 9th edition brings new awareness and reveals a new set of rules. In our evolution as authors we are surfacing as teachers. What we and our reviewers do in class is reflected more in this than in previous editions. Students have always come first in our approach to teaching and textbook authoring, but we now feel more excited than ever about the student-oriented, teacher-friendly quality of this text. We have never included detail for its own sake, but we have felt free to include extra detail if the end result is to clarify. We are especially confident because these new directions have been in response not only to comments from our peers, but more than ever before in response to suggestions from our own students.

To this end we have completely reworked the chapters on cellular metabolism, the muscular system, divisions of the nervous system, endocrine system, nutrition and metabolism, water. and electrolyte and acid-base balance. The final chapter has evolved into "Genetics and Genomics," to acknowledge the completion of the first draft sequence of the human genome, and how this new wealth of information is likely to impact on our understanding of human anatomy and physiology.

• Throughout the text, pronunciation of key terms follows the term as it is first presented within the chapter.
• New vignettes have been written for chapters 6, 15, and 16
• Life-span changes sections have been added to the end of major system chapters.
• A reconnect feature has been added through the text to assist students in referencing helpful information in previous chapters to facilitate the understanding of various concepts.
• Discussion of polar covalent bonds and polar molecules, new figures presenting hydrogen bonds, and the quaternary structure of proteins have been added to chapter 2.
• In chapter 3, diffusion is now described a new movement of particles toward a region of lower concentration, and the etymology of the terms "hydrophilic" and "hydrophobic" are better presented.
• Details of glycoloysis and aerobic pathways have been moved from chapter 4 to the Appendix, and sections on cellular metabolism have been rewritten to clarify the terminology and to present the events in a logical order.
• In chapter 9, the description and definition of the sliding filament model has been clarified, and the structure of muscle and excitation-contraction coupling events are now covered in a more logical and sequential manner.
• The section on sodium and potassium channels and their importance for the resting membrane potential and action potentials has been substantially rewritten in chapter 10, and the discussion of local potential changes and action potentials has been reworked. Impulse conduction is explained more clearly.
• Chapter 11 offers greater clarification of motor versus sensory classification of cranial nerves as well as some new figures of the sympathetic and parasympathetic nervous systems and withdrawal reflex.
• A rewritten explanation of target cells and the importance of their receptors, hormones, and the distinction between exocrine, paracrine and autocrine is part of chapter 13.
• Chapter 15 has improved discussion of filtration in the capillary including osmotic pressure with a new figure illustrating filtration pressures within the capillary
• Chapter 16 has improved discussion of tissue fluid formation including plasma colloid osmotic pressure.
• Chapter 18 now discusses lipid and protein catabolism, which was previously in chapter 4.
• Chapter 19 contains more emphasis on the role of the respiratory system on control of blood pH and better explanation of the inverse relationship between pressure and volume.
• Chapter 20 offers clarification of the roles of aldosterone and atrial natriuretic polypeptide on urinary solute concentration, as opposed to the effect of antidiuretic hormone.
• A simplification of acid-base reactions and clarification of the relationship between renal hydrogen ion excretion and renal bicarbonate ion reabsorption are part of chapter 21.
• Chapter 24 has a "Genomics" approach to reflect the emergence of this new field, and a new clinical application "Gene Therapy Successes and Setbacks" was added.
• Meiosis was moved from chapter 24 to chapter 22.