9.1: Introduction to the Nervous System
By the end of this section, you should be able to:
- 9.1.1 Define the nervous system.
- 9.1.2 Identify the purpose of the nervous system and how it affects the body.
The Nervous System
The nervous system is composed of the central nervous system (CNS) (i.e., the brain and the spinal cord) and the peripheral nervous system (PNS) (i.e., the nerves that extend from the spinal cord to the body). The PNS is subdivided into the somatic nervous system and the autonomic nervous system. Together the CNS and PNS communicate with each other, the organs, and the body to promote homeostasis (see Figure 9.2).
The Nervous System and the Human Body
The nervous system serves as the communication and control system for the human body. This control system, which is essentially composed of all of the nerve cells in the body, regulates everything that we remember, think, and say. It also controls movement and sensation as well as the autonomic responses of breathing, blood pressure, and digestion. It has the unique ability to interact with the environment as well as regulate the activities of the body’s internal organs. Essentially, the nervous system propels the other systems of the body; no other system can function without input from the nervous system. It does so by its composition of structures that transmit electrical and chemical signals between the organs, tissues, and brain.