Book Review

Our Marvelous Bodies: An Introduction to the Physiology of Human Health
Gary F. Merrill
North Carolina, USA: Rutgers Univ. Press, 2008, 240 pages, 22 illustrations, 24 tables, $39.95
ISBN: 978-0-8135-4281-2

According to the author, Our Marvelous Bodies: An Introduction to the Physiology of Human Health is written for a wide audience including, among others, high school students, undergraduate students and allied health students. The overall goals are to demonstrate that physiology is a foundation for medicine, and to show how an understanding of physiology is a useful tool in making decisions about one’s health.

Merrill begins the book with explanations of some foundational concepts that are important in understanding the mechanisms of human body function. In subsequent chapters he explains selected functions of the nervous, endocrine, cardiovascular, respiratory, renal, gastrointestinal, reproductive, muscular, and immune systems. The author finishes each chapter by relating the physiology of the system to health and disease. Merrill describes a lot of personal life-stories to illustrate how physiology is useful in understanding and making decisions that impact one’s health. The author also includes references to the history of physiology and details of specific studies that emphasize the experimental basis of physiology.

The goals of the book are compelling, and the enthusiasm of the author for physiology is evident in the writing. Unfortunately, the book does not achieve expectations. There are a few significant errors and many minor ones that detract from the author’s goals. Overall, I think that a physiology student may become excited about physiology while reading the book, but the student would not improve her understanding of the science.

Having students recognize and understand the foundational concepts in physiology is a proven approach to helping them solve physiological problems. The first chapter aims to explain concepts including structure function relationships, gradients, steady state, equilibrium, homeostasis and control mechanisms. Unfortunately, the discussion of many of these basic concepts does not account for common student misconceptions. For example, the author defines homeostasis using the unqualified terms “constant” and “static” that support the misconception that control systems prevent variables from changing. The book does not include a discussion of the limitations of control systems. Given that students often believe that control systems are capable of returning variables to the set point irrespective of the external conditions, this is a significant omission. The author seems to use steady state and equilibrium as if these terms are interchangeable, and this is also a significant error because many physiology students have difficulty distinguishing between these very different energy states. Merrill explains structure function relationships and gradients more effectively, but, overall, this important foundational chapter is the weakest part of the book.

Subsequent chapters describe the physiology of individual systems and include applications of the physiology to health and disease. Merrill uses some useful and entertaining analogies to simplify the physiology. The quality of these chapters suffers because of the inclusion of a significant number of errors. In some cases the examples that the author uses are misleading. For example, in describing control of ventilation, the author uses an example in which a decrease in the arterial PO2 triggers an increase in ventilation. The example is not inaccurate, but without a corresponding discussion of the relative importance of arterial PCO2 and [H+], the student may erroneously conclude that arterial PO2 is normally the most important of these three controlled variables. Some of the errors in the book reflect a careless use of language. For example, although the author defines physiology as mechanistic, he frequently uses teleological statements as he refers to control systems responding to the “needs” of the body. A few examples of the many careless errors include: the description of a plasma pH of 7.4 as a “neutral,” diffusion across “cell walls” instead of cell membranes, myelinated “nerves” instead of axons. More careful editing is necessary to ensure the accuracy of the explanations.

Many of the examples that are used to relate physiology to health and disease are relevant and interesting. However, in some cases it is not clear why a particular example was used in the context of a particular system. For example, allergies were described in the context of the respiratory system instead of the immune system. Obviously, the symptoms of allergies do manifest as respiratory problems, but an understanding of the mechanisms associated with allergies is an application of the immune system. In other cases, I think that the stories could be edited to more clearly connect to the physiology.

In summary, the goals of the book are worthwhile, and the author is obviously enthusiastic about physiology. I think that students would find many of the analogies and stories in the book interesting. Unfortunately, I am not comfortable recommending the book to students given the number of inaccuracies in this edition. With a significant amount of editing the book could be a useful ancillary to an undergraduate physiology text.

Lynelle Golden
Bastyr University

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