Page 170 - Understanding Psychology

central nervous system (CNS): the brain and spinal cord
spinal cord: nerves that run up and down the length of the back and transmit most messages between the body and brain
peripheral nervous system (PNS): nerves branching out from the spinal cord
The nervous system is never at rest. There is always a job for it to do. Even when you are sleeping the nervous system is busy regulating your body functions. The nervous system controls your emotions, movements, thinking, and behavior.
Structurally, the nervous system is divided into two parts—the central nervous system [CNS] (the brain and the spinal cord) and the peripheral nervous system [PNS] (the smaller branches of nerves that reach the other parts of the body) (see Figure 6.1). The nerves of the peripheral system conduct information from the bodily organs to the cen- tral nervous system and take information back to the organs. These nerves branch out from the spinal column and are about as thick as a pencil. Those in the extremities, such as the fingertips, are invisibly small. All parts of the nervous system are protected in some way: the brain by the skull and several layers of sheathing, the spinal cord by the vertebrae, and the peripheral nerves by layers of sheathing. The bony protection of the spinal cord is vital. An injury to the spinal cord could prevent the transmittal of messages between the brain and the muscles, and could result in paralysis.
HOW THE NERVOUS SYSTEM WORKS
Figure 6.1 The Nervous System
Central Nervous System
Brain Spinal cord
Peripheral Nervous System
Somatic:
controls voluntary muscles
Sympathetic: expends energy
Autonomic:
controls involuntary muscles
Parasympathetic: conserves energy
The nervous system is divided into two parts: the central nervous system (CNS) and the peripheral nervous system (PNS). What are the two main parts of the central nervous system?
156 Chapter 6 / Body and Behavior