1. a set or series of interconnected or interdependent parts or entities (objects, organs or organisms) that act together in a common purpose or produce results impossible by action of one alone.
2. an organized set of principles or ideas.
The parts of a system can be referred to as its elements or components; the environment of the system is defined as all of the factors that affect the system and are affected by it. A living system is capable of taking in matter, energy and information from its environment (input), processing them in some way, and returning matter, energy and information to its environment as output.
An open system is one in which there is an exchange of matter, energy and information with the environment; in a closed system there is no such exchange. A living system cannot survive without this exchange, but in order to survive it must maintain pattern and organization in the midst of constant change. Control of self-regulation of an open system is achieved by dynamic interactions among its elements or components. The result of self-regulation is referred to as the steady state; that is, a state of equilibrium. homeostasis is an assemblage of organic regulations that act to maintain steady states of a living organism.
Definitions of individual systems are to be found under those titles, e.g. alimentary system.
- general s's theory — a theory of organization proposed by Ludwig von Bertalanffy in the 1950s as a means by which various disciplines could communicate with one another and duplication of efforts among scientists could be avoided. The theory sought universally applicable principles and laws that would hold true regardless of the kind of system under study, the nature of its components, or the interrelationships among its components. Since the introduction of the general systems theory, theoretical models, principles and laws have been developed that are of great value to scientists in all fields, including those of medicine, nursing, other health-related professions, and in veterinary medicine.
- heterogeneous s. — a system or structure made up of mechanically separable parts, as an emulsion or suspension.
- homogeneous s. — a system or structure made up of parts that cannot be mechanically separated, such as a solution.
