The nerves extending out from the system go to glands
such as salivary, sweat, liver, and pancreas, and to muscles such as those in
the iris of the eyes, heart, stomach, intestines, and bladder. They also go to
muscles in the walls of blood vessels.
The parasympathetic system consists of
two major nerves. One, the vagus, comes from the medulla and sends branches
through the chest and abdomen. The other, the pelvic, arises from the spinalcord in the area of the hip and sends branches to organs in the lower part of
the body. As examples of how the two systems work: The sympathetic dilates the
pupil of the eye, while the parasympathetic constricts the pupil. Sympatheticnerves speed up the heartbeat; parasympathetic slows it down.
The sympathetic constricts blood vessels and raises
blood pressure; the parasympathetic expands the vessels and lowers pressure.
The autonomic nervous system is influenced strongly by emotions. For example,
when you experience a dry mouth and goose pimples because of fear, the
sympathetic system is at work. Preventing Nervous System Damage Diseases such
as multiple sclerosis and Parkinsonism affect the brain and/ or spinal cord.
These are discussed elsewhere in this book.
Other maladies affect the
peripheral nerves which connect the brain and spinal cord with the muscles,
organs, skin, eyes, etc. When a peripheral nerve is affected, the condition is
called neuritis or neuralgia. And since a peripheral nerve usually contains
both pain and motor fibers, painful symptoms plus some paralysis of muscle
power may occur. Certain toxic materials such as lead, arsenic, and mercury may
pro- duce a generalized poisoning of the peripheral nerves, with pain, tender-
ness, and paralysis of the limbs.
There are many other causes of generalized neuritis,
including alcoholism, vitamin deficiencies, some types of allergy, diabetes,
severe vomiting of pregnancy, thallium toxicity, and some viral and bacterial
infections. While some attacks of generalized neuritis begin with fever and
other symptoms of acute illness, on the other hand, neuritis caused by lead and
alcohol toxicity comes on very slowly over a Course of weeks or months. In most
instances, an attack of generalized neuritis will subside when the toxic
substance is eliminated.
Rest and good diet containing extra vitamins,
especially of the B group, are helpful. Physiotherapy may relieve the pain or
paralysis. Effective prevention of generalized neuritis is based on knowledge
of the danger of poor nutrition, chronic alcoholism, industrial hazards, and
infections-all discussed elsewhere in this book. Frequently, instead of a
generalized irritation of the nerves, only one nerve is afflicted.
For example,
if you sleep in a cold draft which blows on one side of the face, next morning
the facial nerve on that side may be temporarily paralyzed. When produced by
drafts, the paralysis clears up after some days or weeks. After such an episode
revealing your sensitivity to drafts, you will want to take steps, of course,
to avoid recurrence.
