The engineer puts together various components to build a complex system. The biologist dismantles the system to learn something about the components. A system is any part of the universe that a scientist wants to study. In systems analysis a system is defined as a collection of objects or components functioning together according to a set of relationships or laws. Basic components 1.
Physiologists generally apply the black-box approach to living systems.
The stimulus is the signal that provokes the response. In fact, our survival depends on the maintenance of this steady-state. This is the central theme of physiology - homeostasis . Does not imply constancy. All of the mechanisms that are directed toward preservation of the individual.