This book is not a textbook of biophysics, cell biology or the electrophysiology of excitable cells, as there are already a number of excellent books available which deal with these subjects. The book instead is an attempt to describe the origins and derivations of the principles upon which these other books are based.

To understand and apply the principles of excitability requires a knowledge of subjects as diverse as physiology, physics, mathematics, statistics, signal and system analysis. It is a difficult task to obtain this knowledge because the jargon in other fields is often obscure, mathematical proofs are frequently abstruse and generally many original manuscripts have to be consulted. We can both testify to the frustrations that accompany such efforts and this has therefore been written in an attempt to enable the reader to acquire more easily this knowledge. Half of the book is appendices which deal with many of the key concepts from a fairly basic level.

We have assumed that the reader has only a modest mathematical background (about G.C.E. ‘O’ level) and most formulae are derived from first principles. For people with mathematical ability this approach may be somewhat tedious but we make no apologies for this. We consider it necessary that most of the steps in the derivation of an important equation are left in. Far too often have we struggled to follow mathematical proofs that are presented by an author in two lines which in reality take pages to derive.