REVIEW OF THE AUTONOMIC NERVOUS SYSTEM
Section I. INTRODUCTION
a. At some time in your life, you have faced a situation in which you have
undergone a real scare. For example, have you ever been walking down a dark street
at night and heard someone running toward you from behind? At that time, certain
physiological changes took place in your body. Many of these changes directly involved
the autonomic nervous system.
b. The autonomic nervous system (ANS) with its ability to make rapid internal
adjustments is one of the most important systems present in the body in terms of the
maintenance of body balance. The autonomic nervous system is very complex. Almost
every organ of the body receives some type of effect produced by the autonomic
c. Because of the wide distribution of the autonomic nervous system, many
drugs produce definite effects upon it. This can occur as a blockade of natural activity
or a direct effect mimicking natural stimulation. Many so-called side effects of drugs can
also be traced to interference with normal autonomic function. Therefore, you must
have an understanding of how the autonomic nervous system works and how various
drugs can affect its operation. Many drugs used routinely and in emergencies are
classified as autonomic nervous system drugs.
6-2. REVIEW OF THE HUMAN NERVOUS SYSTEM
a. The nervous system is divided into two major divisions--the central nervous
system and the peripheral nervous system. As you will recall, the central nervous
system is composed of the brain and spinal cord. The peripheral nervous system
includes the parts of the nervous system other than the brain and spinal cord.
Figure 6-1 illustrates the division of the human nervous system.
b. The peripheral nervous system has two divisions: the somatic nervous
system and the autonomic nervous system. Figure 6-2 illustrates this division.
(1) Somatic nervous system. The somatic nervous system innervates
skeletal muscle. It is under voluntary control and contains no ganglia. Acetylcholine is
the chemical transmitter in the somatic nervous system (see lesson 2 of this