Biomedical Engineering Reference
In-Depth Information
Figure 3
. Canonical
closed-loop
control system organization depicting the flow of information
as part of the conceptual (cybernetic) model of homeostatic (linear and nonlinear) regulation
(systemic blood pressure and oxygenation). The block diagram generalizes the structure and
function of the "Controller" (e.g., brain) and "Plant" (e.g., cardiovascular system); feedback is
facilitated via chemomechanical sensors (receptors) and other "smart elements" (not easily
localized) that can read signals and appraise status. Self-regulation can be achieved in the
presence of noise or imposed disturbance (e.g., blood loss, posture/altitude changes).
expression and capacity of complex systems to withstand fluctuational changes
from internal and external environments (5,6).
4.
BIOLOGICAL SYSTEMATICS
:
UNDERSTANDING
WHOLE SYSTEMS
Cybernetics also deals with how living systems/subsystems regulate, con-
trol, and reproduce themselves and how, in turn, they can produce other subsys-
tems that are goal-directed, self-regulating, or self-reproducing. Cybernetics is
concerned with understanding the self-organization of human, artificial, and
natural systems including the understanding of its own functioning. Importantly,
cybernetic systems do not have the means to evolve from a lesser to a more dif-
ferentiated state. Cybernetics was part of the systems thinking movement and an
essential component in the growth of scientific knowledge in the 1940s, moti-
vated by a desire to understand life in its entirety.
W. Ross Ashby (7), Norbert Wiener (8), and Warren McCulluch (9) are
credited (albeit, Ashby is less known) with the early formulation of cybernetics
inquiry; they emphasized communication and control, the processes of self-
