Introduction to metabolism
Metabolism is defined as “1. The chemical processes occurring within a living cell or organism that are necessary for the maintenance of life. 2. The processing of a specific substance within the living body.” This definition simplifies a process that occurs at the cellular level in every living being and is the driving process of our existence. The consumption of energy is the basis of life; an innate and evolutionarily honed drive to maintain homeostasis and fulfill the needs for energy and cellular function. Derangements in metabolism are present with every disease process and may even be the cause. The quest to understand the exchange of energy at the cellular level and to develop novel techniques to manipulate, restore, or control this exchange is as old as medicine itself. The goal of this chapter is to review the history of our understanding of metabolic processes, to discuss normal cellular metabolism in a healthy subject, and to identify ways in which metabolism is altered in injury and illness.