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.
Feminist theory. A sociological perspective that emphasizes the centrality of gender in analyzing the social world and particularly the uniqueness of the experience of women. There are many strands of feminist theory, but they all share the desire to explain gender inequalities in society and to work to overcome them.