This book makes an effort an effort to meet the requirement of undergraduate and post-graduate to understand, unless presented in a simple and clear manner. The main objective of the book is to express the fundamental principles and physiological basis of modern medicine in a form which will make the subject clear, lucid and easily understandable to the Indian students of medicine,by avoiding unnecessary or complicated details. While presenting basic fundamentals of physiology and recent concepts that has evolved on the subject, the book strives to present a balanced exposition of the general principles and physiology and experimental research.