內容簡介 The human body is a machine. This machine is composed of organs, which in turn are made of tissues, cells, molecules, atoms, and subatomic particles. And like any physical entity, the human body depends on physical laws. The laws of physics are our basic tool for understanding the functioning of any machine, including biological organisms. Biology is, after all, applied chemistry; and chemistry is really just applied physics. But physical laws by themselves are not sufficient to characterize physical mechanisms. Interaction between elements is of fundamental importance, and a machine is generally better described as a system. The complex machine that we know as the human body is perhaps optimally studied under the umbrella of systems theory.