Transcript Nervous System

Nervous System
Parts of the Nervous System
• Brain
• Spinal Cord
• Nerves
Vocabulary to Know
• Homeostasis
– The regulation of steady, life-maintaining
conditions inside an organism, despite
changes in its environment
Nerve Cells
• Neurons
– Basic functioning units of the nervous
system
http://ilearn.senecac.on.ca/aahs/health/IHP/ottawa/anatomy/neuron/map/neuron.html
http://35.9.122.184/images/40-AnimalStructureAndFunction/
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
Any message carried by a neuron is called an impulse
Neurons
A message carried by a neuron is called
an impulse
Types of Neurons
• Sensory
• Motor
• Interneuron
Sensory Neurons
• Receive information
• Send impulses to the brain or spinal
cord
Interneurons
• Send impulses from sensory neurons
to motor neurons
Motor Neurons
• Conduct impulses from the brain or
spinal cord to muscles or glands
throughout your body
Synapse
• Small space across which an impulse
moves from an axon to the dendrites
or cell body of another neuron
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
http://www.med.harvard.edu/publications/On_The_Brain/Volume7/Number1/images/Neuron.jpg
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
Two Parts of the Nervous System
• Central (CNS)
• Peripheral (PNS)
http://inside.salve.edu/walsh/cns_pns.jpg
Central Nervous System
• Brain
• Spinal cord
The Brain
• Coordinates body activities
• Made up of approximately 100 billion
neurons
• Divided into three major parts– the cerebrum
– the cerebellum
– the brain stem.
Cerebrum
•
•
•
•
•
The largest part of the brain
Where thinking takes place
Where memory is stored
Where movements are controlled
Where impulses from the senses are
interpreted.
Cerebellum
• Interprets stimuli from eyes, ears,
muscles
• Controls voluntary muscle movements
• Maintains muscle tone
• Helps maintain balance
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
http://www.cbituk.org/GRAPHICS/brain.gif
The Spinal Cord
• Extension of the brain stem
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impulses from all parts of the body to
the brain and from the brain to all
parts of your body
The
Peripheral
Nervous
System
Your brain
and spinal
Somatic
cord are
and
connected
Autonomic
to the rest
Systems
of your
The
body by
peripheral
the
nervous
peripheral
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The PNS
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somatic
of 12 pairs
system
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nerves, and
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spinal
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nerves. to
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Spinal
your
nerves are
skeletal
made up of
muscles.
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The
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nerves
contain
both types
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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
http://www.christopherreeve.org/Research/Research.cfm?ID=178&c=21
Peripheral Nervous System
• Two divisions
– Somatic
– Autonomic
http://abdellab.sunderland.ac.uk/lectures/Parmacology/Pics/anatomy/PNS.GIF
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
Autonomic Nervous System
• Controls involuntary actions-those not
under conscious control-such as your
heart rate, breathing, digestion, and
glandular functions
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/autonomic.gif
Reflexes
• Involuntary, automatic response to a
stimulus
• Involves a simple nerve pathway
called a reflex arc