In order to understand why living requires work, and exactly how you get that work done, we need to understand the concepts of work, energy, and entropy. The most basic functions of the human body map...In order to understand why living requires work, and exactly how you get that work done, we need to understand the concepts of work, energy, and entropy. The most basic functions of the human body mapped to the main concepts covered in this text. Later you will examine the similarities between this type of diagram for the human body and that of heat engines, such as the internal combustion engines, which power most vehicles.