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.
Systems theory, at itâs origins, was proposed by Ludwig von Bertalanffy (a biologist) in 1928. Until that point the scientific method had suggested that any system could be broken down into its component parts, and each piece could be analyzed on its own in a vacuum.