THE HUMAN NERVOUS SYSTEM
Section I. INTRODUCTION
The neuron (nerve cell) is the conducting unit of the nervous system. It is
specialized to be irritable and transmit signals, or impulses. The neurons are held
together and supported by another nervous tissue known as neuroglia, or simply glia.
MAJOR SUBDIVISIONS OF THE NERVOUS SYSTEM
The human nervous system can be considered in three major subdivisions:
a. The central nervous system (CNS).
b. The peripheral nervous system (PNS).
c. The autonomic nervous system (ANS).
a. Neuron. A neuron (Figure 12-1) is the nerve cell body plus all of its
processes and coverings.
Figure 12-1. A "typical" neuron.