Abstract
This chapter takes a wider view of the functioning of the mammalian body and reviews the mechanisms of action of hormones and other signal molecules that make sophisticated regulation possible. It describes the feeding–fasting cycle, a physiological process that ensures that adequate energy and nutrient resources are available. The most distinctive characteristic of living organisms is their capacity to sustain adequate, if not always optimal, operating conditions, despite changes in their internal and external environments. The chapter looks at the anabolic and catabolic reaction pathways which use carbohydrates, lipids, and proteins as energy sources and biosynthetic precursors that must be precisely regulated. The operation of such a complex system as the body is maintained by a continuous flow of information among its parts.
