Most physiology textbooks tend to focus on a "snapshot" taken at a particular time of life under standard conditions. This text takes a unique approach to physiology, by empahasizing the adaptations to changing demands, such as age and environment. The ideal complement to standard physiology textbooks, it highlights the importance of considering stressful circumstances and conditions as an aid to understanding normal mechanisms more fully. A completely revised successor to the authors' Variations in Human Physiology, this new book is of immense value to students studying physiology on science courses or preclinical courses in medicine or dentistry.