The transition from the first to the second edition is the most critical stage in a textbook's history, when a book not only demonstrates its staying power in a highly competitive market but also typically undergoes more changes than it will at any later edition. True to pattern, this second edition has undergone hundreds of changes, far beyond what I can list in this preface. I can only give examples here, but a more complete list of changes is provided at the aforementioned website.

This edition has three types of sidebars: 9 "Evolutionary Insights" that show the relevance of the biological history of the body to its present form and function; 17 "Historical Insights" that enliven and humanize the science of A&P through engrossing stories of the men and women behind the facts; and 104 "Clinical Insights" that make the science of A&P relevant to the student's career aspirations and to disorders they may have heard about or experienced. None of these topics-evolution, history, or pathology-are limited to these insight boxes. There are many others, scattered throughout the text in roughly these proportions, ranging from brief mention to extended discussions such as those on diabetes mellitus and immune deficiency diseases.

This edition discusses more than 600 clinical topics, not just in the Clinical Insight boxes but also in the main body of discussion and a new series of tables of common dysfunctions of each organ system. The Clinical Applications list is found in the Instructor's Manual as well as the book website. Dr. Donna Van Wynsberghe, University of Wisconsin-Milwaukee, joined the project with this edition and reviewed the book from cover to cover for clinical accuracy. The new Clinical Applications Manual available for this book expands upon some of the topics briefly described in the book and introduces several new topics and case studies for each organ system.

I have changed a number of terms for closer, but not dogmatic, conformity to the Nomina Anatomica. For example, I replaced spinal column with the more official term vertebral column, but I did not replace Schwann cell with the more official but obscure neurolemmocyte. When there are common, synonymous terms for something, I have been careful to use one term consistently throughout the book-not to use ventral horn in one place and anterior horn in another, for example. Synonyms are introduced parenthetically at the first use of a word. I have also taken added pains to be sure a word is explicitly defined when it is introduced. It is all too easy to name something such as the Golgi complex and immediately begin to describe what it looks like and what it does without ever saying exactly what it is.

Eponyms present a sticky problem for scientific writers. I have avoided most of them, substituting tactile disc for Merkel disc, for example, but some are unavoidable, such as Golgi complex and Alzheimer disease. Stylists have grappled for years with possessive eponyms and the contrary tastes of those who would insist on an apostrophe-s in Cushing's syndrome, yet take offense at the parallel expression, Down's syndrome. The American Medical Association's latest Manual of Style (9th edition, 1998) urges writers to delete the possessive in almost all cases, and I have followed that advice. Thus, you will find in this edition a usage that may seem unfamiliar at first (Bell palsy, Peyer patches) but that is more internally consistent and is now recommended by the AMA. I make exception, as does the AMA, when the nonpossessive form is overly awkward (as Broca area would be), and I retain the possessive form for eponymous laws (Boyle's law, Charles' law).

Aside from these global changes in the book, users of the first edition may notice many specific topics that have been relocated, expanded, condensed, added, clarified, or otherwise modified in this edition. I can give but a few examples here. The numbers in parentheses, except for illustration references, are chapter numbers.

Relocated: Second-messenger systems (4), osmolarity and tonicity (4), and edema (20) have been moved up to earlier chapters because students need an earlier introduction to these topics in order to better understand subsequent chapters. On the other hand, some topics have been moved back to later chapters where they fit better, including the overview of the skeleton and surface markings of bones (9), the ionic basis of membrane potentials (13), subdivisions of the peripheral nervous system (15), auditory ossicles (16), comparison of the nervous and endocrine systems (17), and obesity (26).

Many other topics have been shifted to different places within their original chapters or otherwise regrouped for a more integrated presentation: ionizing radiation (2); endoplasmic reticulum and membrane transport processes (4); rib-vertebra articulations (9); limb muscles (11); neurons, glia, and myelination (13); the ventricles and CSF (14); hypothalamo-pituitary relationships, diabetes mellitus, the synthesis, transport, and action of each class of hormones, and stress physiology (17); the body's three lines of defense, MHC proteins, passive and active immunity, and AIDS (21); intestinal physiology (25); and the ovarian and menstrual cycles (28).

Chapter 1 has been extensively reorganized for better flow. Chapter 6 (Histology) has been restructured to put the specific characteristics of each tissue type into tabular format while retaining a narrative style for more general points about each tissue class, and to present the tissues in the order most instructors say they present them: epithelial, connective, nervous, and muscular.

Added: Topic additions include pericardial, pleural, and peritoneal fluids (atlas A); wound healing (6); stress fractures and pathologic fractures (8); titin and dystrophin (12); disseminated intravascular coagulation (18); cardiac tamponade (19); vaccination (21); a reference table of the gas laws (22); a tabular summary of fluid imbalances (24); the effect of exercise on cholesterol level (25); behavioral thermoregulation (25); gestational diabetes (28); and immunological adaptation of the neonate (29).

New illustrations include coenzyme function (3.19), transmembrane proteins (4.7), the cAMP system (4.9), secondary active transport (4.27), Pap smears (6.13 and in clinical insight 28.1), wound healing (6.35), intramembranous ossification (8.8), feedback loops in calcium homeo- stasis (8.15), eccentric muscle contraction (12.16c), isometric and isotonic phases of muscle contraction (12.17), modes of ATP synthesis during exercise (12.18), temporal and spatial summation (13.22), the duplicity theory of vision (16.36), Cushing syndrome (17.14), the molecular basis of ABO blood types (18.12), and the physiology of Viagra (in clinical insight 27.4). Many other figures were redrawn for clarity, accuracy, or simplicity.

Expanded: Homeostasis (1); free radicals and antioxidants (2); secondary active transport, symport, and antiport systems (4); the regulation of cell division (5); atrophy, apoptosis, necrosis, and tissue repair (6); calcium homeostasis (8); knee injuries (10); ion gate inactivation in action potentials (13); the brain barrier system (14); spinal gating of pain (16); thyroid hormone, somatomedins, cytoplasmic hormone receptors, stress physiology, and the history of insulin (17); the Rh blood group (18); the infant larynx and respiratory diseases (22); the renal countercurrent exchanger (23); control of gastric function (25); and essential fatty acids and ascites (26).

Updated: Some new topics from the recent literature include sunscreens and skin cancer (7); the mechanoreceptive function of osteocytes, the action of parathyroid hormone, and treatment of osteoporosis (8); the genetics of Alzheimer disease (13); the origins of cerebrospinal fluid (14); the umami taste modality (16); melatonin, SAD, and PMS (17); psychoneuroimmunology (21); the genetics and endocrinology of obesity (25); the physiology of Viagra, environmental endocrine disruptors, and sexual transmission of hepatitis B and C (27); and the telomere theory of senescence (29).

Condensed: Some topics were deleted or condensed because reviewers said the first edition had gone into unnecessary detail, and some because it was more important to make room for larger illustrations and new information. Topics now treated more concisely include biomedical history (1), molarity (2), enzymology (3), the sliding filament mechanism (12), cellular mechanisms of memory (13), the evolution and physiology of sleep (14), cranial nerve routes (15), leukopoiesis (18), and infectious diseases of the respiratory system (22).