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Section 11.3
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.
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Health Stats This graph compares bicycle-helmet
use and seat-belt use among teens.
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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).

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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

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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.

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Neuron Structure
Dendrite Dendrites carry nerve impulses toward a
neurons cell body.
Cell Body The cell body controls the cells basic
functions.
Synapse The junction between an axon and
another cell is a synapse. Chemicals called
neurotransmitters pass the impulse from the
sending neuron to the receiving cell.
Axon Impulses travel along axons toward other
cells.
Myelin Sheath Some axons are covered by a myelin
sheath that increases the speed of an impulse.
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Central Nervous System

• The nervous system consists of two major
  divisionsthe 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.

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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
  bodys movements and helps you keep your balance.

• The brain stem consists of three structuresthe
  midbrain, pons, and medulla. These structures
  control many of your bodys involuntary actions.

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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.
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Mixed Messages
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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.
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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.

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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 onlynot the brain.

• Reflexes help protect your body from harm because
  they enable you to react very quickly.

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A Reflex Action
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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.

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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.

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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.

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1) Brain
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2) Spinal cord
3) Peripheral nerves
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Active Art The Nervous System
Click on the screen above to launch the Active
Art.
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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.

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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.

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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.

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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.

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For Updates on overuse injuries
Click above to go online.
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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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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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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.

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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.
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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.
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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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QuickTake Quiz
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For Chapter 11 self test
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• End of Section 11.3
• Click on this slide to end this presentation.