This pioneering book was one of the first to describe the use of advanced mathematical methods in the life sciences. Used widely in one-semester courses, it assumes only elementary calculus and proceeds rapidly, but in a complete and self-contained way, through techniques essential to medicine and biology. Some techniques are unique to this volume and others emphasize the chemical and physical principles underlying biological processes. Less emphasis is given to formal solutions than to methods designed to develop physical intuition and to numerical solutions. Full chapters are devoted to compartmental problems, regulation and oscillation of feedback control systems, numerical methods, diffusion processes, blood flow measurements, curve fitting, and the use of tracers. Unlike most mathematical texts, this book avoids engineering terminology since it is often unfamiliar to biologists. A problem section is included at the end of each chapter, with problems ranging from relatively simple to fairly challenging. Fully worked-out solutions are included for some of the problems. This new fourth edition includes an updated preface and an appendix with sample programs.