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Chapter 3
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NOT FOR SALE OR DISTRI
Introduction to the Structure and
Function of the Nervous System
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Structure and Function of the
Nervous System
makes possible complex activities, such
as walking, running, playing a piano, and
a computer,
as well as simple
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Learning,
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ties, such as maintaining muscle tone and
system
that, along with the endocrine system (see
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posture while at rest.
Chapter 23), controls and coordinates activities
• Monitoring and recognizing stimuli (and
and functions throughout the body, internally
information) within the environment, and
and externally, by sending, receiving, and sortthen directing an appropriate response to
ing electrical impulses. Disruption of any part of
the stimuli. This function
makes possible
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the nervous system affects body function in some
reflex
actions,
such
as
pulling
away
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way, either NOT
internally
or externally.
hand
from
a
hot
surface,
as
well
as
perceivThe nervous system consists of the central
ing music being played in the next room.
nervous system, which includes the brain and
•
Monitoring and coordinating internal body
spinal cord, and the peripheral nervous system,
states so that internal organs function as a
which includes nerve fibers extending from the
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unit, internal
body&constancy
brain and spinal cord that carry information
NOT between
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FORand
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sis) isNOT
maintained,
protective
is
the central nervous system and the rest
taken.
For
example,
in
response
to
a
lack
of
of the body. The peripheral nervous system is furoxygen, more rapid breathing occurs; the
ther divided into two parts: the afferent (sensory)
body shivers in response to cold; and when
system, which carries messages from other parts
threat or danger is encountered, the heart
the body to theLLC
central nervous system, and the
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more rapidly.
efferent (motor) system, which carries messages
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from the central nervous system to other parts of
the body (see Table 3-1).
Other functions, such as display of personality
traits, language, speech, learning, remembering,
feeling emotion, reasoning, and generating and
relaying thoughts, are also controlled by the nerLLC
vous system—specifically, by ©
theJones
brain. & Bartlett
Function of the Nervous System
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Functions of
the nervous
system include
the
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Nerve Cells
• Organizing and directing motor responses
Learnin
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Specialized cells called neurons are the functional units of the nervous system. Neurons
transmit messages
to and
the brain.
They
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consist of NOT
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body and
processes
(nerve
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of the voluntary muscle system, enabling
the body to move more effectively as a
whole
and to achieve
purposeful
movement.
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This
coordination
of
voluntary
muscles
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31
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32 Chapter 3 • Introduction to the Structure
and Function
of the Nervous
System
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process begins again (see Figure 3-1). After neurotransmitters are released, they are either taken
up again by the neuron or destroyed.
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I. Central nervous system
Longer axons are generally grouped in bunNOT FOR SALE OR DISTRI
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A. Brain
dles. When they are transmitting impulses within
the central nervous system, these bundles are
B. Spinal cord
referred to as tracts. Those bundles located outII. Peripheral nervous system
side the central nervous system are referred to
A. Afferent (sensory)
as nerves. © Jones & Bartlett Learning, LLC
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Table 3-1 The Nervous System
(Central and Peripheral)
©
B. Efferent (motor)
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1. Somatic nervous system
2. Autonomic nervous system
a. Sympathetic nervous system
b. Parasympathetic
nervous system
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The Central Nervous System
The central nervous system is made up of the
brain and spinal cord. Bony coverings protect
both the
and the
spinal cord.LLC
On the inte© Jones
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rior of these bony coverings are three membranes
NOT(meninges)
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that provide additional protection:
• The dura mater is the outer membrane,
fibers) that extend beyond the cell body. In most
lying closest to the bony covering of the
cases, a single long nerve fiber called an axon
brain and spinal cord.
conducts nerve
impulses&(and
information)
away
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is the middle
from the cell
body
to
other
neurons.
Smaller,
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membrane, a cobweb-appearing
membrane.
shorter nerve fibers called dendrites conduct
• The pia mater is the inner membrane, which
nerve impulses toward the cell body after receivlies closest to the brain and spinal cord.
ing information from other neurons. Fibers that
carry information from parts of the body to the
Between each of the membrane layers are spaces.
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brain &
areBartlett
called afferent
neuronsLLC
(sensory neuThe space between
the dura
mater andLearning,
the inner
NOT rons).
FOR Fibers
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information from the
surface of NOT
the bony
covering
the epidural
brain to other parts of the body are called efferspace. T; the space between the dura mater and
ent neurons (motor neurons).
the arachnoid membrane is the subdural space;
Surrounding neurons is a fatty sheath called
and the space between the arachnoid membrane
myelin, which, much like the covering of elecand the pia mater is the subarachnoid space.
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Learning,
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cords, provides
The&central
nervous
system is also
protected
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electrical impulses are able to flow smoothly and
and cushioned by cerebrospinal fluid (CSF),
reliably. Information is passed from neuron to
which is formed by specialized capillaries called
neuron by both electrical and chemical impulses.
the choroids plexus in inner chambers within the
The electrical impulse, which has been picked up
brain called ventricles. The cerebrospinal fluid
by the dendrites, is passed through the cell body
bathes the brain and spinal cord, circulating from
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to the axon. The electrical impulse then moves
the ventricles into the subarachnoid space (see
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down the full length of the axon until it reaches
Figure 3-2). From the subarachnoid space it the
its tip. At the tip of the axon are tiny processes,
CSF flows to the back of the brain, down around
which release chemicals known as neurotransthe spinal cord, and then back to the brain,
mitters. Neurotransmitters, through chemical
where it is reabsorbed into the blood through the
means,
transfer
the
impulse
from
one
neuron
arachnoid membrane.
amounts ofLearning,
cerebro© Jones & Bartlett Learning, LLC
© JonesThe
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to
another
across
a
space
between
the
two
neuspinal
fluid
produced
and
absorbed
are
equally
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rons called the synapse. The electrical impulse,
balanced, so that under normal conditions, the
through the vehicle of neurotransmitters, then
amount of CSF within the central nervous system
moves to the next neuron’s dendrites and the
remains constant.
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Structure
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Figure 3-1 Neurons
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harmful substances, such as toxins, are prevented
Another protective device is the blood–brain
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from crossing into the brain.
barrier, a structural arrangement of capillaries
The central nervous system is composed of
that selectively determines which substances can
white matter and gray matter. White matter
move from the blood into the brain. While submakes up the inner part of the brain and the outer
stances such as oxygen and glucose are necessary
portion of the
cord&and
consists of
myelinto brain
survival and
consequently
move freely
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ated
covered
axons
that
conduct
nerve
impulses.
across
the
blood–brain
barrier,
other
potential
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Figure 3-2 Circulation of Cerebrospinal Fluid
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34 Chapter 3 • Introduction to the Structure
and Function
of the Nervous
System
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It is called white matter because of its whitish
• The associational cortex is involved in cogappearance due to the myelin covering. Gray
nitive functions such as memory, reasoning,
matter makes
up
the
thin
outer
layer
of
the
brain
© Jones & Bartlett Learning, LLC abstract thinking, and consciousness.
© Jones & Bartlett Learnin
and the inner portion of the spinal cord. Small
FORcalled
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The cerebrum is divided into NOT
two halves,
segments of gray matter are also embedded deep
the right hemisphere and the left hemisphere.
within certain parts of the white matter of the
These two hemispheres communicate with each
brain. Gray matter consists of groups of neuron
other. Dividing the hemispheres and connecting
cell bodies; it gets its name from . It is called gray
specific areas of the two hemispheres are bundles
matter&because
of itsLearning,
grayish appearance.
© Jones
Bartlett
LLC Gray
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of nerve fibers called the corpus callosum. Each
matter
of
the
brain
receives,
sorts,
and
processes
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FORfor
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ORinformaDISTRIBUTION
hemisphereNOT
has centers
receiving
nerve messages, while gray matter of the spinal
tion and for initiating responses. The left hemicord serves as a center for reflex action (automatic
sphere mostly receives information from and
response to stimuli).
sends information to the right side of the body,
whereas
right hemisphere
mostly
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LLCreceives
from and sends information to the
Structure
and Function of
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NOTinformation
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left side of the body.
the Brain
Deep within the cerebral hemispheres are
The brain is directly connected to the spinal cord
groups of gray matter called basal ganglia, which
and serves as the primary center for the integraare part of the extrapyramidal system. (“Extrapytion, coordination, initiation, and interpretation
ramidal” denotes nerve fiber tracts
that lie outside
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Jones
&
Bartlett
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of most nerve messages. It regulates and monithe
pyramidal
tract,
a
relatively
compact
group
of
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tors many unconscious
functions,
such as
nerve fibers that originate from cells in the outer
heart and respiratory rate, and coordinates most
layer of the brain.) Extrapyramidal function is
voluntary movements. In addition, it is the site
concerned with postural adjustment and gross
of higher cognitive processes such as learning,
voluntary and automatic muscular movements.
generating
and relaying
thoughts,
reasoning,
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The basal ganglia
help to
tone
in musjudgment, memory, consciousness, and emotion.
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NOTand
FOR
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OR DISTRIBUTION
cles in the trunk
extremities,
indiThe brain also has a sensory function, which is
viduals to maintain balance and posture and to
responsible for vision, hearing, touch, taste, and
engage in movements such as walking. The basal
smell. Language function, including the ability
ganglia also play a role in enabling individuals to
to communicate and to comprehend, is also conreact swiftly, appropriately, and automatically to
by the brain
as well. Finally, the brain conones & Bartletttrolled
Learning,
LLC
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stimuli&that
demand an
immediate response,
trolsDISTRIBUTION
basic behavior patterns and the display of
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after tripping, enabling the individual to adjust
general personality traits, which are characterishis or her movement to avoid a fall.
tic of how each individual responds to stimuli.
Each hemisphere of the cerebrum is divided
The brain is protected by the bony covering of
into lobes that contain areas related to specific
the skull (cranium or cranial bones). The largest
functions (see Figure 3-3). The frontal lobe is
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part of the brain,
the cerebrum,
is covered
with a
located in the front of each hemisphere and conthin outer layer
of FOR
gray matter
called
cortex,
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tains motor areas that initiate voluntary movewhich contains billions of nerve cells. The cortex
ment and skilled movements, such as those,
has three specialized areas, which serve three
involved in handwriting. Other areas in the fronmajor areas of function:
tal lobe control higher intellectual functions such
•
The
motor
cortex
coordinates
voluntary
as foresight,©analytical
and Learning,
judgment.
© Jones & Bartlett Learning, LLC
Jones thinking,
& Bartlett
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movements
of
the
body.
The
parietal
lobe
is
located
in
the
middle
of
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• The sensory cortex is responsible for the
each hemisphere and is primarily the sensory
recognition or perception of sensory stimarea, integrating and interpreting sensation such
uli, such as touch, pain, smell, taste, vision,
as touch, pressure, pain, and temperature. Some
and hearing.
memory functions are also located in the parietal
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Structure
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Function
of the Brain 35
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Figure 3-3 Areas of Brain Function
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lobe, especially those responsible for storage of
articulation. This area contributes to expressive
sensory memory. The temporal lobe is located
function (speech formation), or the ability to inteunder the frontal and parietal lobes and is prigrate and coordinate words so that the meaning
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Learning,
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marily&responsible
the interpretation
can be comprehended.
NOT distinction
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ORlies
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between
stimuli. The occipiA structure
known
as the
thalamus
within
tal lobe is located at the back or posterior porthe center of the brain. The thalamus acts as a
tion of each hemisphere; i. It is the primary area
relay station that sorts, interprets, and directs
for reception and interpretation of visual stimuli.
sensory information. Below the thalamus is the
Several parts of the cerebrum are involved
hypothalamus, which coordinates neural and
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the language function, which consists of the
endocrine
activities. It
This structure
helps reguT FOR SALE OR
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OR
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process of receiving, interpreting, and integratlate the body’s internal environment and behaving visual and auditory stimuli as well as the
iors that are important to survival, such as eating,
ability to express thoughts in a coordinated way
drinking, and reproduction. Below the hypothalaso that others can comprehend them. Language
mus is the pituitary gland, an endocrine gland that
function is located in the left hemisphere of the
will be discussed in more detail in a later chapter.
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cerebrum in most individuals, whether they are
The limbic system is comprises a group of
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right- or left-handed. An area located over the
structures consisting of bothNOT
gray FOR
and white
temporal and parietal lobes, called Wernicke’s
matter that surround the thalamus. The limbic
area, is the major area responsible for receptive
system plays a role in expression of instincts,
function (speech understanding), or the ability to
drives, and emotions and as in the formation of
integrate
visual
and
auditory
information
so
as
memories. A
of gray
called
the hip© Jones & Bartlett Learning, LLC
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Jones
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to
understand
communication
received.
An
area
pocampus
is
involved
in
learning
and
long-term
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located in front of the temporal lobe and in the
memory, helping to determine where important
frontal cortex, called Broca’s area, is responsible
and relevant aspects of facts will be stored.
for speaking ability and is closely associated with
Beneath the occipital lobe of the cerebrum is
motor areas that control the muscles needed for
a structure called the cerebellum. The cerebellum
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36 Chapter 3 • Introduction to the Structure
and Function
of the Nervous
System
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is primarily responsible for the coordination and
fused (joined) bone. At the tip of the sacrum is
integration of voluntary movement and for the
the coccyx, or tailbone (see Figure 3-4).
maintenance
of
equilibrium,
posture,
and
balance
© Jones & Bartlett Learning, LLCThe spinal cord conducts©impulses
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of the body. It also regulates and coordinates fine
from the brain. The outer white matter of the
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movements of the extremities, which are initiated
spinal cord, which consists of bundles or tracts of
by the frontal lobe.
myelinated fibers of sensory (afferent) and motor
The brain stem, which is located beneath
(efferent) neurons, conveys electrical impulses up
the cerebellum at the base of the brain just above
and down the spinal cord between the peripheral
the spinal
cord, actsLearning,
as a relay station,
nervous system
(those nerves
lying outside
the
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ting
nerve
impulses
between
the
spinal
cord
and
central
nervous
system)
and
the
brain.
In
most
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the brain. It is the primary center of involuntary
instances, sensory information traveling up the
functions. Control of vital organ functions, such
right side of the spinal cord crosses over to the
as regulation of heartbeat or respiration, occurs in
left side of the brain, so the left hemisphere of
the brain would, for example, interpret pain in
the brain stem. Areas in the brain stem also reguones & BartlettlateLearning,
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Bartlett
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of blood vessels, contributing to
the right
Conversely,
motor impulses
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NOTnating
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the control
of blood pressure. Reflex actions, such
the leftOR
brainDISTRIBUTION
cross to the right side of
as coughing and swallowing, are controlled in the
the spinal cord and initiate a response to the right
brain stem as well. Finally, the brain stem conside of the body. Because of this crossover effect,
tains scattered groups of cells, called the reticudamage on one side of the brain typically causes
lar formation, which are involved in the initiation
manifestations itself on the opposite side of the
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and maintenance of wakefulness and alertness.
body.
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The brain
requires
both
oxygenOR
and DISTRIBUTION
nourishment in the form of glucose in order to function
Figure 3-4 The Spine
and to survive. Oxygen and glucose are transported to the brain by blood carried by four major
arteries:
two carotidLearning,
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two vertebral
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arteries. The vertebral arteries join to form the
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basilar artery. The carotid and basilar arteries
then connect at the base of the brain to form the
circle of Willis, from which cerebral arteries
branch out to carry blood to the rest of the brain.
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Structure
and Function
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of the Spinal Cord and
Peripheral Nervous System
The Spinal Cord
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the centralLearning,
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extends
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stem
to the
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OR
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lower part of the back. Bony coverings called
vertebrae surround the spinal cord and protect
it. Taken as a whole, this bony covering, as a
whole, forms the vertebral column. The vertebral
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column
of 7Learning,
cervical vertebrae,
NOT in
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the neck area; 12 thoracic vertebrae, located
in the upper and middle back; and 5 lumbar vertebrae, located in the lower back. The sacrum,
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located below the lumbar vertebrae, consists of
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Structure and Function of theNOT
SpinalFOR
Cord SALE
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Nervous System 37
OR DISTRIBUTION
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The inner gray matter of the spinal cord,
Many types of neurons work together to transwhich is composed of cell bodies and unmymit impulses through the spinal cord. Sensory
elinated neurons,
acts as
coordinating
center LLC
impulses entering the spinal cord
at the lumbar
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for reflex and other activities, such as voluntary
region are relayed vertically to the brain through
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movements and control of internal functions. A
a number of connecting sensory neurons. Motor
reflex center in the gray matter of the spinal cord
impulses from the brain to the peripheral nerves,
is where sensory and motor neurons connect; this
however, are conducted through two separate catpart of the spinal cord serves as a center for spinal
egories of motor neurons. Upper motor neurons
reflexes.
reflex canLearning,
be defined asLLC
an automatic
originate in ©
theJones
brain and
contained
entirely
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Bartlett
&are
Bartlett
Learning,
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response
to
a
given
stimulus.
Spinal
reflexes
conwithin
the
central
nervous
system.
Lower
motor
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trol not only muscle reflexes, but also the reflexes
neurons, although originating in the central nerof internal organs.
vous system, have fibers extending to the periphThe gray matter within the spinal cord resemeral nerves in voluntary muscles. Alteration of
bles the letter “H.” The projections of the H are
function of either upper or lower motor neurons
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Learning,
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& Bartlett
accordingLLC
to the direction to which they
can generally
affect Learning,
the voluntary LLC
muscles. The
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NOTlocation
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project.
The posterior horns extend toward the
of the alteration
of function determines
back, and the anterior horns project toward
the nature of the manifestations.
the front. Cerebrospinal fluid, which nourishes
Structure and Function of the Peripheral
and protects the spinal cord, fills both the cenNervous System
tral canal, located within the center of the gray
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A nerve is a bundle of fibers outside the cenmatter, and the subarachnoid space surrounding
NOT information
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NOTofFOR
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tral nervous system that transmits
the outer portion
the spinal
cord.OR DISTRIBUTION
between the central nervous system and variMotor (efferent) impulses originate in the
ous parts of the body. The peripheral nervous
motor cortex of the brain, extend down the spinal
system consists of all nerves that extend from
cord through descending tracts, and exit through
the brain and
cord.&ToBartlett
function effectively,
motor
spinal
nerve
roots
that
extend
through
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©spinal
Jones
Learning, LLC
the peripheral nerves must be connected to the
openings between the vertebrae that surround the
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central nervous system. Some peripheral nerves
spinal cord. Sensory (afferent) impulses from the
connect directly to the brain (cranial nerves);
body enter the spinal cord through spinal nerve
others connect directly to the spinal cord (spinal
roots that also extend through openings between
nerves). Cranial and spinal nerves are essential
vertebrae and then travel up ascending tracts in
links between
the restLearning,
of the body and
the central
the
spinal
cord
to
the
brain.
ones & Bartlett Learning, LLC
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& Bartlett
LLC
nervous
system.
Spinal
nerve
roots
are
named
for
the
verteT FOR SALE OR DISTRIBUTION
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The 12 pairs of peripheral nerves that conbral level from which they exit. For example, the
nect and transmit messages directly to the brain
nerve roots that leave the spinal cord at the cerviare called cranial nerves. Some cranial nerves
cal level are labeled C1 through C8, and the nerve
contain only sensory fibers, whereas others conroots that leave at the thoracic level are labeled
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& Bartlett
Learning,
LLC
© Jones
& Bartlett Learnin
tain both sensory and motor fibers.
Cranial nerves
T1 through©
T12
(see Figure
3-5). The
sensory
mediate many aspects of sensation
muscular
(afferent) nerve
outside
theDISTRIBUTION
central
NOTand
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SALE OR DISTR
NOTfibers
FORfrom
SALE
OR
activity in and around the head and neck. Cranial
nervous system carry body sensations into the
nerves and their related functions are described
sensory nerve roots (posterior roots) at the back
in Table 3-2).
of the spinal cord, where they are then carried
The 31 pairs of peripheral nerves that conup the spinal cord to the brain. Motor (efferent)
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&
Bartlett
Learning,
LLC
© Jones
& Bartlett
LLC
nect and transmit
messages
directly to Learning,
the spinal
impulses travel from the brain down the spinal
NOT cord
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OR
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OR
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cord are called spinal nerves. Each nerve divides
exit from motor nerve roots (anterior
and then subdivides into a number of branches.
roots) at the front of the spinal cord. Motor nerve
Nerves at each level travel to specific parts of
fibers then carry impulses to the voluntary musthe body, conveying information between those
cles of the body.
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ones & Bartlett Learning, LLC
38 Chapter 3 • Introduction to the Structure
and Function
of the Nervous
System
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FOR SALE
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Figure 3-5 Spinal Nerves
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T FOR SALE OR DISTRIBUTION
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areas and the
central nervous
system.
Spinal
The autonomic nervous system
integrates
the
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& Bartlett
Learning,
LLC
© Jones
& Bartlett
Learnin
nerves and NOT
their related
functions
are
described
work
of
vital
organs,
such
as
the
heart
and
lungs.
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in Figure 3-5.
Its primary function is to coordinate the activity
Nerves control both voluntary and involunof internal organs so that they can make adaptary functions in the body. Nerves that control
tive responses to changing external situations,
voluntary functions (such as movement of the
thereby maintaining internal equilibrium. Nerve
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& Bartlett
Learning,
LLC somatic fibers monitor
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Learning,
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muscles
in the extremities)
are called
the activities
of internal
organs
Nerves that
concerned with the conas well as changes
in the SALE
external OR
environment.
NOT nerves.
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ORare
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trol of involuntary functions are part of a subcatWhen changes are necessary to maintain interegory of the peripheral nervous system called the
nal homeostasis (equilibrium) or to protect the
autonomic nervous system.
body, the autonomic nervous system stimulates
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Bibliography 39
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Table 3-2 Cranial Nerves and Related Functions
© Jones
Cranial Nerve
I.
& Bartlett
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Area of Learning,
Function
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OR DISTRIBUTION
Smell
Olfactory
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II. Optic
Vision
III. Oculomotor
Movement of eye muscles
IV. Trochlear
Eyelids
VII. Facial
Taste, sensation of external ear, control of salivary glands, tears, muscles in
facial expression
VIII. Vestibulocochlear
Sensation of sound, balance, orientation of head
© Jones
Bartlett Learning,
LLCin head, face, and teeth, motor
© activity
Jonesof &
Bartlett Learning, LLC
V. &
Trigeminal
Sensation
chewing
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VI. Abducens
Pupil dilation, focusing of lens
ones & Bartlett IX.
Learning,
LLC
Glossopharyngeal
T FOR SALE OR
X.DISTRIBUTION
Vagus
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& Bartlett
LLC
Swallowing, sensation
of pain, taste,
touch fromLearning,
tongue and throat
NOT
FOR
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OR DISTRIBUTION
Heartbeat, digestion,
speech,
swallowing,
function, gland functions
XI. Accessory
Movement of head and shoulders, muscles of pharynx and larynx in throat,
production of voice sounds
XII. Hypoglossal
Tongue movement, speech, swallowing
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an immediate, involuntary response. For example, in response to a speck of dust in the eye, tears
are produced; i. In response to a fearful situation,
the heart beats faster.
© JonesThe
& autonomic
Bartlettnervous
Learning,
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system is divided into
NOT two
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subsystems:
• The sympathetic nervous system
• The parasympathetic nervous system
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In contrast, the parasympathetic nervous
system dominates when the body is a rest. It
activates those mechanisms that focus on body
conservation, such as decreasing the heart rate
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and constricting the pupils of the eye. The paraFOR
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sympatheticNOT
nervous
system
is alsoOR
an important
component of sexual arousal in both males and
females.
two systems work both together and in
ones & BartlettThese
Learning,
LLC
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& Bartlett Learning, LLC
Bibliography
opposition to control internal organs and reguT FOR SALE OR
DISTRIBUTION
NOT
FOR
SALE OR DISTRIBUTION
late their function. Hormones and emotions can
Falvo, R. E. (2001). Human physiology physiology 201 core
curriculum. Champaign, IL: Stipes Publishing L.L.C.
affect both systems.
Sherwood, L. (2007). Human physiology: From cells to sysThe sympathetic nervous system becomes
tems (6th ed.). Australia:. Thomson Brooks/Cole.
active during periods of stress and in emergenTortora,
G. J., & Derrickson, B. H. (Eds.). (2011).(13th ed)
cies. It prepares
the body
action, deepening
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& for
Bartlett
Learning, LLC
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Principles of anatomy and physiology (13th ed.). Hoborespirations,NOT
making
the heart
beat faster,
dilating
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OR DISTRIBUTION
ken, NJ:. John Wiley and Sons. NOT FOR SALE OR DISTR
the pupils, stimulating production of stress horWidmaier, E., Raff, H., & Strang, K. (Eds.). (2010). Vander’s
mones, and increasing blood supply to the large
human physiology: The mechanisms of body function.
muscles of the body.
New York: McGraw-Hill.
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