Psychology2016

56 CHAPTER 2

understanding how all the different parts work together in controlling the way people

and animals think, act, and feel.

The Central Nervous System: The “Central Processing Unit”

2.4 Describe how the brain and spinal cord interact and respond to external

experiences.

The central nervous system (CNS) is composed of the brain and the spinal cord. Both

the brain and the spinal cord are composed of neurons and glial cells that control the life-

sustaining functions of the body as well as all thought, emotion, and behavior.

THE BRAIN The brain is the core of the nervous system, the part that makes sense of the

information received from the senses, makes decisions, and sends commands out to the

muscles and the rest of the body, if needed. Many different areas of the brain are involved

in preparing us for an appropriate response to the information received, and the brain is

responsible for cognition and thoughts, including learning, memory, and language. Later

parts of this chapter will cover the brain in more detail, but for now, you should know

the brain is organized into different regions, each with primary functions. While the neu-

rons in each of the different areas work in much the same way, it is the groups of cells and

the connections between them and other parts of the brain or components of the nervous

system, and our experiences, that influence the various functions found in specific brain

areas (Amaral & Strick, 2013; Heimer, 1995; Squire & Kandel, 2009).

THE SPINAL CORD The spinal cord is a long bundle of neurons that serves two vital func-

tions for the nervous system. Look at the cross-section of the spinal cord in Figure 2. 6. Notice

that it seems to be divided into two areas, a lighter outer section and a darker inner section.

If it were a real spinal cord, the outer section would appear to be white and the inner section

Figure 2.5 An Overview of the Nervous System

The brain and spinal cord

Central nervous system

Transmits information to

and from the central

nervous system

Peripheral nervous system

Automatically

regulates glands,

internal organs

and blood vessels,

pupil dilation,

digestion, and

blood pressure

Autonomic

nervous system

Carries sensory

information

and controls

movement

of the skeletal

muscles

Somatic

nervous system

Prepares the

body to react

and expend

energy in times

of stress

Sympathetic

division

Maintains body

functions under

ordinary

conditions;

saves energy

Parasympathetic

division

Carries messages

from CNS to

muscles and

glands

Motor system

(efferent)

Carries messages

from senses to

CNS

Sensory system

(afferent)

Interprets and

stores information

and sends orders

to muscles, glands,

and organs

Brain

Pathway

connecting the

brain and the

peripheral

nervous system

Spinal cord

Nervous system

central nervous system (CNS)
part of the nervous system consisting
of the brain and spinal cord.

spinal cord
a long bundle of neurons that carries
messages between the body and the
brain and is responsible for very fast,
lifesaving reflexes.