Biomedical Engineering Reference
In-Depth Information
The ICNS has many of the complex attributes associated with the CNS,
incorporating afferent and efferent components mediating its activity. This form
of functional organization provides the heart with the ability to fine tune its
adaptive organ-system response. The inherent capacity of the cardiac ganglionic
neurons to respond to local mechanical and chemical stimuli may facilitate the
means for the adaptive intrinsic mechanism to operate under stress and patho-
physiologic conditions (i.e., neuropathy, transplantation, and aging). Ultimately,
the intrinsic regulatory neurogenic mechanisms of the ICNS along with the CNS
mutually negotiate the functional role that the autonomic nervous system plays
in the control of the automaticity, electrical propagation, and contractility of the
heart (12).
Likewise, there is compelling evidence of distributed feedbacks with multi-
ple overlapping and surprisingly conflicting short-term goals in the immune
system (see chapters 4.1 [by Segel] and 4.2 [by Kepler], Part III, this volume).
Information about and progress toward goals are being monitored from sensor
detection and are broadcast to the system via vectors of signaling chemicals (i.e.,
cytokines). This sensor-driven strategy of distributed feedbacks helps improve
the performance of a preferentially selected effector cell.
4.2. Multilevel (Hierarchical/Heterarchical) and Distributed Organization
Living systems are organized such that they manifest operational features
ascribed to hierarchical and heterarchical structures. The functional organization
is inherently a heterarchy of interrelations and as such has no obvious or fixed
order rank. Unlike machines and/or mechanisms, the functional hierarchy does
not dictate level and importance of cooperativity.
No man is an island—he is a holon. A Janus-faced entity who,
looking inward, sees himself as a self-contained unique whole,
looking outward as a dependent part.
—Arthur Koestler
The basic rules of distributed cooperation (i.e., superposition of system
upon system) are inspired by precepts of holarchy, defined (4) as a hierarchical
organization of self-regulating entities (holons) that function as autonomous
wholes in supraordination to their parts and as dependent parts in subordination
to controls on higher levels defining their function. This superposition perspec-
tive implies that natural systems are organized such that every system level (see
Figure 1) is constrained by the immediate next level above it and similarly by
the supporting level below it. This arrangement, in coordination with the local
