Open System (glossary)
A system which exchanges inputs and outputs with its environment. (von Bertalanffy 1968)
von Bertalanffy, L. 1968. General system theory: Foundations, development, applications, Revised ed. New York, NY: Braziller.
Open system theory considers an organism as a complex entity composed of many parts with an overall integrity, co-existing in an environment. In an open system the organisms structure is maintained, or adapts, through a continual exchange of energy and information with its environment.