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Section 11.3 Your Nervous System
Your Nervous System
Objectives
Explain the functions of the nervous system
and the role of neurons.
Describe the roles of the central nervous
system and the peripheral nervous system.
Identify the most important thing you can do to
keep your nervous system healthy.
Slide 1 of 34
Section 11.3 Your Nervous System
Health Stats This graph compares bicycle-helmet use and seat-
belt use among teens.
Why do you think many more teens wear seat belts
than bicycle helmets?
Slide 2 of 34
Section 11.3 Your Nervous System
What Is the Nervous System?
• Your nervous system receives information about
what is going on inside and outside of your body.
• Then it processes the information and forms a
response to it.
• The basic unit of the nervous system is a type of cell
called a neuron (NOOR ahn).
Slide 3 of 34
Section 11.3 Your Nervous System
Neuron Structure
• Neurons carry messages, or impulses, from one part
of your body to another.
• A neuron has three basic parts.
• dendrites
• a cell body
• an axon
Slide 4 of 34
Section 11.3 Your Nervous System
Types of Neurons
• Sensory Neurons Information about your external
and internal environment is gathered by sensory
neurons through your sense organs or other parts of
your body.
• Interneurons Located only in the brain and spinal
cord, interneurons pass impulses from one neuron to
another.
• Motor Neurons Motor neurons send nerve
impulses to muscles and glands.
Slide 5 of 34
Section 11.3 Your Nervous System
Neuron Structure
Dendrite
Dendrites carry nerve
impulses toward a
neuron’s cell body.
Cell Body
The cell body controls
the cell’s basic functions.
Axon Synapse
Impulses travel along The junction between
axons toward other cells. an axon and another
cell is a synapse.
Chemicals called
Myelin Sheath neurotransmitters pass
Some axons are covered the impulse from the
by a myelin sheath sending neuron to the
that increases the speed receiving cell.
of an impulse.
Slide 6 of 34
Section 11.3 Your Nervous System
Central Nervous System
• The nervous system consists of two major
divisions—the central nervous system and the
peripheral nervous system.
• The central nervous system is the control center of
the body. It includes the brain and spinal cord.
• The peripheral nervous system includes all the other
parts of the nervous system.
Slide 7 of 34
Section 11.3 Your Nervous System
The Brain
• The cerebrum consists of several specialized
regions that receive messages from sense organs,
and control movement, memory, communication, and
reasoning.
• The cerebellum (sehr uh BEL um) coordinates your
body’s movements and helps you keep your
balance.
• The brain stem consists of three structures—the
midbrain, pons, and medulla. These structures
control many of your body’s involuntary actions.
Slide 8 of 34
Section 11.3 Your Nervous System
Slide 9 of 34
Section 11.3 Your Nervous System
Mixed Messages
Test how well your brain can handle conflicting messages.
Material
watch or clock with second hand
Try This
Read the list of words while your partner times how long
it takes you.
Notice that the words in the list are written in different
colors. This time you should say the color of each word
as your partner times you. Do not read the words,
rather, identify their colors.
Slide 10 of 34
Section 11.3 Your Nervous System
Mixed Messages
Slide 11 of 34
Section 11.3 Your Nervous System
Mixed Messages
Think and Discuss
Did it take you more time to read the words or say the colors?
Describe the experience of saying the colors.
Which part of your brain most likely works hardest during this
activity? Which task is your brain better at—reading the words
or identifying their colors?
Once people master basic skills such as tying shoes or
reading, they perform them with little thought. How do you
think this fact affected your results in this activity?
What do you think would happen if you asked a young child
who has just learned to read to do this activity? Explain.
Slide 12 of 34
Section 11.3 Your Nervous System
The Spinal Cord
• The spinal cord is a thick column of nerve tissue
that links the brain to most of the nerves in the
peripheral nervous system.
• The spinal cord extends from the brain down the
back.
• Spinal nerves are part of the peripheral nervous
system.
Slide 13 of 34
Section 11.3 Your Nervous System
Reflexes
• An automatic response to your environment is called
a reflex.
• In some reflex actions, the actions of the skeletal
muscles are controlled by the spinal cord only—not
the brain.
• Reflexes help protect your body from harm because
they enable you to react very quickly.
Slide 14 of 34
Section 11.3 Your Nervous System
Sensory neurons in your
hand send impulses A Reflex Action
to your spinal cord.
Neurons in your spinal
cord process the
information and send
commands directly
to motor neurons that
control muscles in your
arm and hand.
Your muscles contract and
you quickly withdraw your hand.
Meanwhile, messages of pain travel
to the brain. Shortly after your arm
moves, you feel pain.
Slide 15 of 34
Section 11.3 Your Nervous System
Peripheral Nervous System
• The peripheral nervous system includes the network
of nerves that links the rest of your body to your
brain and spinal cord.
• The peripheral nervous system carries information to
the central nervous system, and then carries
responses from the central nervous system to the
rest of the body.
Slide 16 of 34
Section 11.3 Your Nervous System
Sensory Division
• Some nerves in the sensory division carry
information about your outside environment from
your ears, eyes, and other sense organs.
• Other sensory nerves carry information about
internal body conditions such as blood pressure and
heart rate.
Slide 17 of 34
Section 11.3 Your Nervous System
Motor Division
• Somatic Nervous System Motor nerves in the
somatic nervous system carry signals that control
voluntary actions.
• Autonomic Nervous System Motor nerves in the
autonomic nervous system regulate actions that
happen automatically.
Slide 18 of 34
Section 11.3 Your Nervous System
1
2 1) Brain
2) Spinal cord
3) Peripheral nerves
3
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Section 11.3 Your Nervous System
Active Art: The Nervous System
Click on the screen above to launch the Active Art.
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Section 11.3 Your Nervous System
Keeping Healthy
• Rest, good nutrition, and daily exercise can help
keep your nervous system functioning properly.
• The most important step you can take to care for
your nervous system is to protect it from injury.
Slide 21 of 34
Section 11.3 Your Nervous System
Avoiding Head Injuries
• A bruiselike injury to the brain is known as a
concussion.
• A coma is a prolonged period of deep
unconsciousness.
• Head injuries can be avoided.
• Wear a helmet when you play contact sports.
• Fasten your seat belt.
• Before diving into water be sure that it is deep
enough and that there are no underwater
hazards.
• Avoid drugs and alcohol.
Slide 22 of 34
Section 11.3 Your Nervous System
Avoiding Spinal Cord Injuries
• Paralysis is the loss of the ability to move and feel
some part of the body.
• Spinal cord injuries can be avoided
• Fasten your seat belt.
• Take care when diving.
• Avoid drugs and alcohol.
Slide 23 of 34
Section 11.3 Your Nervous System
Avoiding Nerve Injuries
• Individual peripheral nerves also can be injured.
• To help prevent carpal tunnel syndrome and similar
nerve injuries, it is important to take breaks from
repetitive motions and to maintain good posture.
Slide 24 of 34
Section 11.3 Your Nervous System
For: Updates on overuse injuries
Click above to go online.
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Section 11.3 Your Nervous System
Preventing Infections
• Nervous system infections are rare because its
tissues are well protected.
• Meningitis (men in JY tis) causes inflammation of the
membranes surrounding the brain and spinal cord.
• The most serious form of meningitis can be
prevented with a vaccine.
• A bite from an infected animal can transmit rabies,
an infection of the central nervous system.
• Avoid contact with animals that act sick or behave
strangely.
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Section 11.3 Your Nervous System
Living with Epilepsy
• Sudden, uncontrolled nerve impulses in the brain
can lead to a seizure.
• People with a disorder called epilepsy are prone to
seizures.
• Epileptic seizures include facial twitching, loss of
awareness, and muscle spasms.
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Section 11.3 Your Nervous System
Slide 28 of 34
Section 11.3 Your Nervous System
Preventing Headaches
• The most common problem of the nervous system
that people experience are headaches.
• Proper diet, exercise, and sleep can help prevent
headaches.
• If you can identify certain foods or odors that trigger
headaches, you may be able to avoid those triggers.
Slide 29 of 34
Section 11.3 Your Nervous System
Vocabulary
neuron The basic unit of the nervous system that
carries nerve impulses.
cerebrum A part of the brain that contains several
specialized regions that receive messages from
sense organs, and control movement, memory,
communication, and reasoning.
cerebellum A part of the brain that coordinates movements
and balance.
brain stem The area of the brain between the cerebellum and
the spinal cord; it controls automatic functions such
as heartbeat and blood pressure.
Slide 30 of 34
Section 11.3 Your Nervous System
Vocabulary
spinal cord A thick column of nerve tissue in the central
nervous system that links the brain to most of
the nerves in the peripheral nervous system.
reflex An automatic response of the nervous system to
the environment.
concussion A bruiselike injury to the brain caused by brain
tissue hitting the skull during a collision.
coma A prolonged period of deep unconsciousness.
paralysis The loss of the ability to move and feel some
part of the body.
Slide 31 of 34
Section 11.3 Your Nervous System
Vocabulary
meningitis An infection that causes inflammation of the
membranes surrounding the brain and spinal
cord.
seizure An episode of erratic nerve impulses in the brain
that may lead to loss of consciousness, muscle
spasms, and other uncontrollable symptoms.
epilepsy A condition in which a person is prone to
seizures.
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Section 11.3 Your Nervous System
QuickTake Quiz
Click to start quiz.
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Section 11.3 Your Nervous System
For: Chapter 11 self test
Click above to go online.
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Section 11.3 Your Nervous System
End of Section 11.3
Click on this slide to end this presentation.
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