The goal of physiology is to explain the physical and chemical factors that are responsible for the origin, development, and progres- sion of life.Therefore, the vast field of physiology can be divided into viral physiology, bacterial physiology, cellular physiology, plant physiology, human physiology, and many more subdivisions.Thus, the human being is, in many ways, like an automaton, and the fact that we are sensing, feel- ing, and knowledgeable beings is part of this automatic sequence of life; these special attributes allow us to exist under widely varying conditions.