Structure, function, differentiation, and integration. The relationship between these concepts is of
crucial importance for understanding living systems. It is easy to see organization as a structure of
parts and to explain system behavior in terms of relations between the parts, causes and effects,
stimulus and response. Our understanding of living systems warns against such reduction, emphasizing
that structure, function, behavior, and all other features of system operation are closely intertwined.
Although it is possible to pursue the study of organisms through the study of anatomy, a full
understanding of such systems calls for much more. Even the life of the simple cell is dependent on a
complex web of relations between cellular structure, metabolism, gas exchange, the acquisition of
nutrients, and numerous other functions. The cell as a system is a system of functional interdependence
that is not reducible to a simple structure. Indeed, the structure at any one time depends on the
existence of these functions and in many respects is only a manifestation of them. The same is true of
more complex organisms, which reflect increased differentiation and specialization of function (e.g.,
with specialized organs performing specific functions)and which thus require more complex systems
of integration to maintain the system as a whole (e.g., through the operation of a brain). Similar
relationships between structure, function, differentiation, and integration can also be seen in social
systems such as organizations.