[Systems theory and nursing--a theoretical discussion]

Every nurse interested in nursing process models and nursing theory will sooner or later meet the general systems theory (GST). In this article the background of GST is briefly described. Further the key concepts of GST are defined; components, attributes, relations, borders, input, output, filtering, process, open system, closed system, subsystem, suprasystem, feedback and steady state. As examples of GST in nursing the Newman Health Care Systems Model, the Johnson Open System Model and Yura and Walsh way of using the theory are described in brief. Finally some advantages and disadvantages of using general systems theory in nursing are noticed.