Physiology is the branch of biology that studies normal mechanisms and their interactions within a living system. It focuses on how organisms, organ systems, cells and biomolecules interact and perform the chemical and physical functions in a living system. Human physiology explores the mechanical, physical and biochemical functions in humans. The human body is constituted by many interacting systems of organs. These systems include the nervous system, endocrine system, respiratory system, circulatory system, etc. The interactions of these systems are essential for the maintenance of homeostasis. Each system is important for the functioning of the body. This book is a compilation of chapters that discuss the most vital concepts in the field of human physiology. Different approaches and evaluations of human physiology have been included in this book. It is appropriate for those seeking detailed information in this area.