Students of physiology are faced with more quantitative information such as ion concentrations, fluid volumes and blood pressures than ever before. Here, using simple calculations, the reader has an opportunity to develop a feel for such figures, give them meaning, and above all to derive fresh insights from them. These calculations are neither brain-teasers nor mere practical exercises, and require little more than easy arithmetic. Guidance is also given on the tricks of approximation and back-of-envelope arithmetic and on coping with the varied systems of units that encumber physiology. The main areas covered are energy metabolism, nerve and muscle, blood and the cardiovascular system, respiration, renal function, body fluids and acid–base balance.The book is intended as supplementary reading for students of physiology at any level, including graduates who seek new slants on the subject.