Interacting with chatty Dr Dee

These "books" with identical main titles emanate from West Virginia, Texas and Michigan. I say "books", because all three are actually gateways to interactive learning systems, of which the printed form is but a part.

Lauralee Sherwood has written a text for "undergraduate students preparing for health-related careers", for adoption by a one-semester American college course. It is not specifically for medical students. Sherwood shares her enthusiasm for the subject. Each chapter includes sections under: "Concepts, challenges and controversies", which includes "high-interest, tangentially relevant information"; "A closer look at exercise physiology", which reflects "the importance of physical fitness" and "Growing career opportunities Related to fitness and exercise"; "Chapter in perspective: focus on homeostasis", which explains "how the part of the body just discussed contributes to homeostasis"; and "Points to ponder".

It is unclear how this fourth edition differs from its predecessors. Seven "ancillaries" are mentioned. The homepage of one states: "Offer available to North American colleges and universities only."

"Physioconcepts.com" led into links, some of which provided animations and soundtracks. One - "determining blood pressure" - showed blood flow through an arm with a picture of a sphygmomanometer, accompanied by an earnest female voice, but no Korotkoff sounds actually to be heard - a missed opportunity surely? If we are going to have multimedia, let us exploit it. Another ancillary is "Web Tutor on WebCT", but in spite of logging on to the website, it was unclear how to proceed from that point. There are four ancillary manuals - a study guide, a lab manual, a booklet of case histories and a full-colour photo atlas; I saw none of these.

In summary, Sherwood provides a gateway to a complex learning system. It claims to have a "capstone" feature (I think that means "overarching", but British dictionaries are of little help), which is an emphasis on homeostasis - a concept introduced in the first chapter without reference to Claude Bernard or W. B. Cannon. Indeed, a criticism of the book is that it provides many facts, but physiology is not presented as a subject relying on experiment and observation.

With Dee Silverthorn we are, from the outset, urged to love "Dr Dee", as she likes us to call her; we see that she composes at her word-processor with two dachshunds on her lap. She does not specify her target audience, but the overall level suggests that this book is in direct competition with Sherwood for the lucrative one-semester college market. The book reflects the author's concern to do a thorough pedagological job. She starts each chapter with a list of "Background Basics". She encourages the reader to hop around within the book to seek clarification of a particular topic using a blue "chain-link" icon. The text of each chapter is interrupted with so-called concept checks, ensuring that the reader has grasped what has gone before. At the end of each chapter is a set of questions ranging from factual to problem-solving.

Within chapters there are focus boxes, which provide nuggets of text linking to biotechnology, clinical practice, emerging concepts or diabetes. There is a useful glossary-plus-index, combining a brief definition as well as page references for each word. All in all, not a relaxing fireside read. Each chapter concludes with a set of "Explore MediaLab" web exploration tasks, which require the reader to log on to a website ( http://cwx. prenhall.com/bookbind/pubbooks/silverthorn2/ ) created to accompany the book. The site seems well presented, but is associated with the usual frustrations. It has copious links to sites that are not controlled by the book's publishers, so if these change or close down, they become inaccessible unless updated. The first task I tested out - a link to the word Everest - took me, after a long delay, to an unhelpful error message. This is a difficulty when publishing instructions for using the web, which assume that the linked sites are properly maintained. If too many of the links fail to work, the eager web-browser can easily become discouraged.

Components of the associated website reveal slovenly proof-reading, such the following words from one question: "reffering", "acylcholine" and "actylcholine". But such a vast enterprise is bound to have flaws. This book seems more grounded in experimental work and in the history of the subject than Sherwood's.

With Arthur Vander et al , we have an author who is an established name in physiology textbooks; another Vander effort, his little monograph on renal physiology, sets a high standard for brevity and clarity. The present larger book is aimed at the American college market - including students of liberal arts, biology, nursing and pharmacy; it is not intended to provide full coverage for medical students. Vander is in its eighth edition (it started in 1970). The preface explains how this edition differs from its predecessor. It lists: major changes to the illustrations (with a lot of colour coding and ever more use of the flow diagrams so loved by Vander), and updating of subject matter - it was good to know the details of topics updated.

There is a mass of supplemental material, notably the "Essential study partner" on a pair of CD-Roms, which I had some trouble in loading on to my (otherwise fully functional) computer. There is also a tailor-made website to accompany the book, from which it is but a couple of clicks from some good links, as some idiosyncratic ones (eg www.pathguy.com/index2.htm ).

The site offers chapter-by-chapter support for the book's reader, and the online assessments seem useful. There is a further mass of supportive material separately available (though not provided to me for review) including videotapes of animations, a "virtual physiology lab" and a web-based workbook of problems to be solved.

Web-based books were new to me; an interesting idea - it seems you have to buy a password - which seems a reasonable way of gaining some recompense for the labour of creating the work. So what is the verdict? It must lie between Silverthorn and Vander. As a stodgy old physiologist, I felt more comfortable with Vander, though I suspect that some students might prefer the chattier style of Silverthorn.

Alan L. R. Findlay is senior tutor and director of studies in medical sciences, Churchill College, Cambridge.