This is the updated and thoroughly revised edition of the popular textbook, fondly dedicated to the memory of Dr CC Chatterjee who had written the book in the Independence era of country in 1948. Dr Chatterjee was the faculty at Calcutta Medical College. This book was widely read throughout the country and South East Asia for over four decades and helped medical and paramedical students to have firm understanding of the functional aspects of human body. Dr Chatterjee passed away in 1984 but his book still remains in the minds of millions of readers who read it with passion. He wrote a complete integrated physiology textbook with anatomy and biochemistry encompassed altogether in the era when there were no computers or any advance technology for printing. The integrated approach of incorporating anatomy, physiology and biochemistry in this single textbook was marveled by all academicians and was one of the salient features of the book of all the eleven editions up to 1984.