Biomedical Engineering Reference
In-Depth Information
Figure 2
. Abstract representation and synthesis of "Complex Systems," including their con-
stituent hierarchical organization entities (components/elements) and dynamic relations (rela-
tional emergent function). Note that order and common behavior may arise from both self-
organization and control structures. (Artwork by M. Clemens.)
control (Figure 3). Emphasis is placed on the mechanistic relations that hold
between the different parts of a system (i.e., input-sensors, controller-centers,
output-effectors). The basic premise of cybernetics is the transfer of information
and the circular relations that define feedback, self-regulation, and autopoiesis.
Cybernetics contributed the understanding of goal-directedness or purpose made
possible by a negative feedback loop that minimizes the deviation between out-
come and desired goal (Figure 3). The brain-body coupling plays a prominent
role in the cybernetic model of regulation and control. The foundation of closed-
loop autonomic control is information transmission and the enabling communi-
cation pathways, facilitated by sensors (i.e., chemoreceptors, mechanorecep-
tors/pressoreceptors) and effectors (e.g., sympathetic drive, endocrine release)
that couple neural processes (e.g., medulla) to myriad regulatory processes (Fig-
ures 3 and 5). Considerable overlap exists between regulatory cycles and centers
of the limbic system and the various homeostats that constitute the endocrine,
immune, and nervous systems. A disturbance to organismic regulation can occur
at multiple levels and is prone to modulation by sleep, wakefulness, and emo-
tional states. These closely coupled interactions give rise to a dynamic equilib-
rium of the controlled process, manifested as homeodynamic stability, an
