ANATOMY AND PHYSIOLOGY OF THE NERVOUS SYSTEM
The nervous system facilitates contact of the individual with his external and
internal environments and aids in appropriate responses to these constantly changing
environments. A general knowledge of the anatomy of the nervous system and an
understanding of its physiology will help you to recognize and treat injuries and
diseases of the nervous system.
ROLE OF THE NERVOUS SYSTEM
a. The nervous system has three general functions that it performs in the role of
the body's control center and communication network. The functions are:
(1) The nervous system is able to sense change both inside the body and
change in the environment surrounding the body.
The nervous system is able to interpret these changes.
(3) The nervous system causes the body to react to these changes by either
muscular contraction or glandular secretion.
b. Homeostasis is a good example of the nervous system sensing change,
interpreting change, and adjusting to change. (In homeostasis, the equilibrium of
factors such as temperature, blood pressure, and chemicals are kept in relative
balance.) In the case of homeostasis, the nervous system and the endocrine system
ORGANIZATION OF THE NERVOUS SYSTEM
The nervous system has two main divisions: the central nervous system (CNS)
and the peripheral nervous system (PNS). The central nervous system is composed of
the brain and the spinal cord. This system controls behavior. All body sensations are
sent by receptors to the central nervous system to be interpreted and acted upon. All
nerve impulses that stimulate muscles to contract and glands to secrete substances get
the message from the central nervous system. The peripheral nervous system is
composed of nerves. This system is a pathway to and from internal organs. PNS
serves as a pathway to the brain for the five senses and helps humans adjust to the
world around them. Further subdivision of the peripheral nervous system will be
discussed later in this lesson.