Biology Reference
In-Depth Information
11.4 Principal Organisation of the Defence and
Defeat Reactions
Regulation of body function is organized at different hierarchical levels, where those of
the central nervous system (CNS) are of decisive relevance when it comes to environ-
mental stimuli. Thus, CNS constitutes the highest level in the hierarchy of control sys-
tems that direct the responses to both internal and environmental stimuli.
Figure 11.3
illustrates in schematic form the hierarchic organisation in higher organisms, from
neocortex down to intracellular organelles and the genetic code. At each level of
control, functions are balanced-off by negative feedback mechanisms, according to
the principles of “homeostasis”.
I. CNS control level
Efferent Links:
Somatomotor-behavioral
Autonomic
Neuroendocrine
Neocortex
Paleocortex
Environmental
stimuli
Hypothalamus
Pituitary
II. Brain stem
Regulatory function on
brain stem level (e.g., medulla)
Baro- and
volume receptor
input
Chemoreceptor
input
III. Organ level
Local positive and negative
feedback on organ level
IV. Cellular level
Tissue and cellular function
V. Subcellular level
Organelles, membranes
VI. Molecular and genetic level
Molecular design function
and genetic level
Figure 11.3
Outline of the six main levels of hierarchical organisation and control in higher
organisms (adapted from Folkow B. Ann Behav Med 1993;15(4):236-244).
