The book is written system wise. The theme includes the way alterations are produced in normal physiology by disease, leading to the generation of symptoms and signs. This approach is expected to help the student appreciate the role of basic sciences in understanding the pathophysiology of disease. Simple flow charts and diagrams are used to explain the text. For each chapter there is a Short Questions-Answers module which offers explanation to the questions raised in the text. The book has been treated keeping in view the environmental and socio economic factors that control lives in India.There has been no attempt to deal with every mundane subject in the field of physiology. In each chapter only certain aspects of the subject have been dealt with. The areas chosen are generally found interesting by most students. Two chapters namely Circadian Rhythms and Pathophysiology of Stress, and Pathophysiology of Thermoregulatory Disorders are new innovations.The aim of the book is to enthuse the student into thinking in “Clinical terms” using basic sciences as back drop and to conceptualize and derive conclusions rather than memorize facts.