Eric Widmaier (Boston University), Hershel Raff (Medical College of Wisconsin), and Kevin Strang (University of Wisconsin) have taken on the challenge of maintaining the strengths and reputation of this book. Moving beyond the listing of mere facts, it stresses the causal chains of events that constitute the mechanisms of body function. The fundamental purpose of this textbook is to present the principles and facts of human physiology in a format that is suitable for undergraduates regardless of academic background or field of study. This thirteenth edition, carries on the tradition of clarity and accuracy, while refining and updating the content to meet the needs of today's instructors and students. The thirteenth edition features a streamlined, clinically oriented focus to the study of human body systems. It has also responded to reviewer requests for more clinical applications. Physiology Inquiries are maintained throughout the chapters. These critical-thinking questions associated with figures are just one more opportunity to add to the student.s learning experience.