There is a biochemical and anatomical difference. Exhausted would implies that there is no available energy for the task at hand and enervated would suggest that the intended task lack the nervous potential to be actuated. That said, in popular discourse, there is not much difference between the two.
Systems theory has also been developed within sociology. An important figure in the sociological systems perspective as developed from GST is Walter Buckley (who from Bertalanffy's theory). Niklas Luhmann is also predominant in the literatures for sociology and systems theory.
Family Systems Theory - Basic Concepts/propositions. One of the central premises of family systems theory is that family systems organize themselves to carry out the daily challenges and tasks of life, as well as adjusting to the developmental needs of its members. Critical to this premise is the concept of holism.