This book presents basic concepts and principles of normal gastrointestinal physiology and, most importantly, conveys an understanding of how to apply this knowledge to abnormal gastrointestinal physiology in the clinical context. The ultimate goal of this work is to let the readers have an integrated systems-based approach in order to be able to grasp knowledge on gastrointestinal disease and its management. Human gastrointestinal physiology is the study of our gastrointestinal system that addresses the regulation and integration of major physiological functions, i.e. motility, secretion, digestion, absorption and blood flow, as well as immunity. The coordination of these physiological processes is vital for the maintenance of gastrointestinal health, and thus any dysregulation will result in gastrointestinal disease. In this book, the understanding of basic gastrointestinal concepts and principles are illustrated by scenario-based clinical case presentations, critical for bedside care and also for preparation for professional examinations, and for being able to deal with future developments in clinical care. In this handbook, the aim is to achieve these various objectives by covering the breadth of gastrointestinal system. The contents are, therefore, designed to fall systemically into three core sections, namely Gastrointestinal Physiology (Part I), Nutritional Physiology (Part II) and Hepatobiliary Physiology (Part III), with closely relevant scenario-based clinical case studies at the end of each chapter to help students learn to apply their growing knowledge of basic gastrointestinal science, in the clinical setting. Last but by no means least, we provide a wide range of multiple-choice-questions (Part IV) so that students can evaluate their understanding of the basic science in each area of the GI system and to develop the students' ability to apply their knowledge to solving clinical problems.