The Sympathetic Nervous System
Associated with the central nervous system by connecting nerves--but
located outside of it in various parts of the body--are groups of
nerve-cells (gray matter) and their fibers, forming what we call the
sympathetic nervous system--the direct connecting link between mind
and body.
The central nervous system is the director of all conscious action of
the body; the sympathetic orders all unconscious action.
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The beating of the heart, the contraction of the blood-vessels, hence
the flowing of the blood, the processes of digestion, the functioning of
the glands, are all directed by the sympathetic. In other words, the
central nervous system normally controls the movements of the
voluntary muscles; the sympathetic controls those of the involuntary
muscles.
The quick blush, the sudden paling of the cheeks, the start of fear, the
dilated pupils of fright are the direct result of the action of
involuntary muscles under control of the sympathetic system. The
stimulus is received by the central nervous system; the fibers
connecting the central and the sympathetic systems carry the message
quickly to the latter, which immediately respond by ordering contraction
or expansion of involuntary muscles. So tears flow, we breathe freely
again or we quake and tremble, our pupils widen or contract, the heart
beats suffocatingly, or seems almost to stop.
The sympathetic system, as the name implies, is influenced by
suggestions from the emotions rather than from the intellect. We might
say that it is controlled by the "feeling mind" rather than the thinking
mind, for intellect cannot influence it in the least.
The wise nurse, who knows something of the laws of the mind, soon
realizes that the sympathetic nervous system, rather than physical
disability, causes many indigestions, headaches, diarrheas, dry mouths,
chills; is responsible for much nausea, much "exhaustion," etc. When she
has had wider experience she finds that almost any known physical
disorder can be unconsciously imitated by the suggestible patient, whose
sympathetic nervous system causes physical reactions to respond to the
feelings of a sick mind. Let the nurse remember, however, that is it not
for her to decide whether the disorders from which her patient suffers
are of physical or nervous origin. It is for her, on the other hand, to
study her patient's mentality and reactions, and to become expert in
reporting symptoms of nervous as well as of physical significance.