Problem solving is an indispensable part of learning a quantitative science such as neurophysiology. This text for graduate and advanced undergraduate students in neuroscience, physiology, biophysics, and computational neuroscience contains comprehensive, mathematically sophisticated descriptions of modern principles of cellular neurophysiology. It provides detailed derivations of equations, worked examples, and homework problem sets (with complete answers). Developed from notes for the course that the authors have taught since 1983 at Baylor College of Medicine, USA, this text covers cellular neurophysiology (also some material at the molecular and systems levels) from its physical and mathematical foundations.