Nervous System

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Nervous System
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Parts of the Nervous System

• Brain
• Spinal Cord
• Nerves

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Vocabulary to Know

• Homeostasis
• The regulation of steady, life-maintaining
  conditions inside an organism, despite changes in
  its environment

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Nerve Cells

• Neurons
• Basic functioning units of the nervous system

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http//ilearn.senecac.on.ca/aahs/health/IHP/ottawa
/anatomy/neuron/map/neuron.html
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http//35.9.122.184/images/40-AnimalStructureAndFu
nction/
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Neurons

• Made up of a cell body and branches called
  dendrites and axons
• Dendrites receive messages from other neurons and
  send them to the cell body
• Axons carry messages away from the cell body

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Any message carried by a neuron is called an
impulse
Any message carried by a neuron is called an
impulse
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Neurons

• A message carried by a neuron is called an
  impulse

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Types of Neurons

• Sensory
• Motor
• Interneuron

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Sensory Neurons

• Receive information
• Send impulses to the brain or spinal cord

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Interneurons

• Send impulses from sensory neurons to motor
  neurons

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Motor Neurons

• Conduct impulses from the brain or spinal cord to
  muscles or glands throughout your body

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Synapse

• Small space across which an impulse moves from an
  axon to the dendrites or cell body of another
  neuron

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Synapse

• An impulse reaches the end of an axon
• Axon releases a chemical
• Flows across the synapse
• Stimulates the impulse in the dendrite of the
  next neuron
• Impulse moves from neuron to neuron

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http//www.med.harvard.edu/publications/On_The_Bra
in/Volume7/Number1/images/Neuron.jpg
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An impulse moves in only one direction across a
synapse - from an axon to the dendrites or cell
body of another neuron.
http//mhln.com
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Two Parts

• Central (CNS)
• Peripheral (PNS)

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http//inside.salve.edu/walsh/cns_pns.jpg
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Central Nervous System

• Brain
• Spinal cord

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The Brain

• Coordinates body activities
• Made up of approximately 100 billion neurons
• Divided into three major parts-
• the cerebrum
• the cerebellum
• the brain stem.

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Cerebrum

• Largest part of the brain
• Thinking
• Memory is stored
• Movements are controlled
• Impulses from the senses are interpreted.

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Cerebellum

• Interprets stimuli from eyes, ears, muscles
• Controls voluntary muscle movements
• Maintains muscle tone
• Helps maintain balance

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Brain Stem

• Connects brain to spinal cord
• Made up of the midbrain, the pons,
• Act as pathways connecting various parts of the
  brain with each other
• Medulla
• controls involuntary actions

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http//www.cbituk.org/GRAPHICS/brain.gif
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The Spinal Cord

• Extension of the brain stem
• Bundles of neurons that carry impulses from all
  parts of the body to the brain and from the brain
  to all parts of your body

extension of the brain stem. It is made up of
bundles of neurons that carry impulses from all
parts of the body to the brain and from the brain
to all parts of your body
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The Peripheral Nervous System Your brain and
spinal cord are connected to the rest of your
body by the peripheral nervous system. The PNS is
made up of 12 pairs of nerves from your brain
called cranial nerves, and 31 pairs from your
spinal cord called spinal nerves. Spinal nerves
are made up of bundles of sensory and motor
neurons bound together by connective tissue. For
this reason, a single spinal nerve can have
impulses going to and from the brain at the same
time. Some nerves contain only sensory neurons,
and some contain only motor neurons, but most
nerves contain both types of neurons.
Somatic and Autonomic Systems The peripheral
nervous system has two major divisions. The
somatic system controls voluntary actions. It is
made up of the cranial and spinal nerves that go
from the central nervous system to your skeletal
muscles. The autonomic system controls
involuntary actions-those not under conscious
control-such as your heart rate, breathing,
digestion, and glandular functions. These two
divisions, along with the central nervous system,
make up your body's nervous system.
                                              
                                                  
                                                  
                                                  
                                                  
                     Research Visit the Glencoe
Science Web site at tx.science.glencoe.com for
more information about the nervous system. Make a
brochure outlining recent medical advances.



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Peripheral Nervous System

• Connects body to brain spinal cord
• 12 pairs of nerves from your brain (cranial
  nerves)
• 31 pairs from your spinal cord (spinal nerves)
• Bundles of sensory and motor neurons held
  together by connective tissue

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http//www.christopherreeve.org/Research/Research.
cfm?ID178c21
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Peripheral Nervous System

• Two divisions
• Somatic
• Autonomic

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http//abdellab.sunderland.ac.uk/lectures/Parmacol
ogy/Pics/anatomy/PNS.GIF
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Somatic Nervous System

• Controls voluntary actions
• Made up of the cranial and spinal nerves that go
  from the central nervous system to your skeletal
  muscles

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Autonomic Nervous System

• Controls involuntary actions-those not under
  conscious control-such as your heart rate,
  breathing, digestion, and glandular functions

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http//users.rcn.com/jkimball.ma.ultranet/BiologyP
ages/A/autonomic.gif
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Reflexes

• Involuntary, automatic response to a stimulus
• Involves a simple nerve pathway called a reflex
  arc

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