Animal physiology and Biochemistry is the scientific study of the life-supporting properties, functions and processes of animals or their parts. General physiology studies the physiological principles common to different species, the reactions of living organisms to stimuli, and the processes of excitation and inhibition. The electric phenomena occurring in the living organism, that is, its bioelectrical potentials are investigated by electrophysiology. The phylogenetic development of physiological processes in different species of invertebrate and vertebrate animals is the concern of comparative physiology. Comparative physiology is in turn the basis of evolutionary physiology, which studies the origin and evolution of the life processes in relation to the general evolution of the organic world. The book explains the fundamentals of animal physiology, while providing an integrative learning experience, drawing on ideas from chemistry, physics, mathematics, molecular biology and cell biology for its conceptual underpinnings. This book is meant both for graduate students as well as for the faculty members.