Principals of neural functioning Motor Nervous System
As stated before, the nervous system accomplishes a wide
range of tasks, and for that, a single cell isolated model isn’t
likely functional, as a matter of fact, the overall functioning of
the CNS is based on the interaction between many populations
of neurons, with a network where each neuron receives (by the
dendrites) and emits (with the axon) millions of
electrochemical impulses every day, the nature of this
connections (linear, loops, divergent or convergent), their
number and the nature of the synapses (inhibitory or
excitatory) and the specialization of the composing elements
determine the nature of these circuits, taking for instance the
simple well studied re�lex arc, an external dangerous stimulus
causes the stimulation of a peripheral sensory organ in the
tegument, the impulse is transmitted to the corresponding
segment of the spinal cord through the sensory nerve, which
(supposing a monosynaptic re�lex) -after entering the spinal
cord- will transmit an excitatory message to the motoneuron
that will cause muscle contraction after receiving the output
through the motor nerve, the circuits of other functions are
more complicated, including polysynaptic, divergent and many
nervous centers interactions generating tons of intrinsic
electrical discharge patterns. From this analysis, we can
distinguish three functional sectors of the nervous system that
work in a linear way: Sensory, integrative and motor sectors. After determining the output, the CNS sends back these
adjustments via the motor pathways to the effectors (Muscles
or glands mainly) in order to keep the integrity of the body and
maintain the different biological parameters of the internal
milieu within the limits of physiological conditions.
Worth mentioning at last, that nothing is absolute about all of
these divisions, as of the appearance of new proofs every day,
especially in Neuroscience research �ields, about new different
functioning patterns, which can only support the complexity of
this system and the extend of its adaptation capacities, and new
model is emerging more today, one that suggests a combination
of area specialization and overall discharge patterns, a model,
that only days can con�irm or refute.
References
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Clinically oriented anatomy (6th ed., [International ed.]. ed.).
Philadelphia [etc.]: Lippincott Williams & Wilkins, Wolters
Kluwer. ISBN 0-652-60547-1-978.
- Bear, Mark F.; Barry W. Connors; Michael A. Paradiso (2007).
Neuroscience: Exploring the Brain: Third Edition. Philadelphia,
PA,
USA:
Lippincott
Williams
&
Wilkins.
ISBN
4-6003-7817-0-978.
- Campbell, Neil A.; Jane B. Reece; Lisa A. Urry; Michael L. Cain;
Steven A. Wasserman; Peter V. Minorsky; Robert B. Jackson
(2008). Biology: Eighth Edition. San Francisco, CA, USA: Pearson
/ Benjamin Cummings. ISBN 4-6844-8053-0-978.
- Kandel ER, Schwartz JH (2012). Principles of neural science (5.
ed.). Appleton & Lange: McGraw Hill. ISBN 8-139011-07-0-978.
- Kent, George C.; Robert K. Carr (2001). Comparative Anatomy of
the Vertebrates: Ninth Edition. New York, NY, USA: McGraw-Hill
Higher Education. ISBN 5-303869-07-0.
- Maton, Anthea; Jean Hopkins; Charles William McLaughlin;
Susan Johnson; Maryanna Quon Warner; David LaHart; Jill D.
Wright (1993). Human Biology and Health. Englewood Cliffs,
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- Romer, A.S. (1949): The Vertebrate Body. W.B. Saunders,
Philadelphia. (2nd ed. 3 ;1955rd ed. 4 ;1962th ed. 1970)
Sensory Nervous System
It is the body’s main tool to understand what happens in the
surroundings (environment) and inside of it (interior milieu),
the sensory nervous system is a set of receptors that code the
data they receive about the corresponding stimuli (and their
parameters) into an electrical impulse in a process called
transduction. The receptors are specialized structures with the
ability to receive certain perturbations (pressure, vibration,
light, sounds, heat…..), to recognize them, and to de�ine their
parameters (intensity, modality and topography) to eventually,
transform this data into a wave of action potentials to be
transmitted later on, to the corresponding treating areas in the
CNS, while the function model of some modalities is relatively
simple (like somatic sensory receptors), nothing is simple
about the functioning of others (the eye for instance, contains
more than seven neural populations and connects with almost
every structure in the superior CNS).
Integrative Nervous System
Here again, the activit y of neural circuits is on its best, after the
arrival of sensory input to the concerned areas, a data
treatment sequence is initiated, implicating the interaction of
many neural populations, pre-determined program sequences
comparison and other sensory modalities feedback, the CNS
comes to the adequate responses and determines the
modi�ication and the adjustments compatible with the current
state, this complex process is called integration and unlike the
relatively clear lateralization and somatotopic arrangement in
the sensory and the motor sector of the nervous system, the
integrative function is very heterogeneous and has little respect
to principles of area specialization in the CNS, to this special
complex sector, attributed most of the high mental processes of
memory, emotions (limbic system), language and abstract
thinking, faculties englobed by the name of cognition.
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