Transcript Peripheral Nervous System

Nervous System
Parts of the Nervous System
• Brain
• Spinal Cord
• Nerves
Vocabulary to Know
• Homeostasis
–The regulation of steady, lifemaintaining conditions inside
an organism, despite
changes in its environment
Function
• This system works to pass
electrical messages from
sensory nerves to the brain.
• The brain interprets the
message then sends a
response to motor neurons.
The Neuron
• Neurons
–Basic functioning units of the
nervous system
http://ilearn.senecac.on.ca/aahs/health/IHP/ottawa/anatomy/neuron/map/neuron.html
Under the microscope…
http://35.9.122.184/images/40-AnimalStructureAndFunction/
Neurons
• Made up of a (1)cell body and
branches called (2)dendrites and
(3)axons
– Dendrites receive messages from
other neurons and send them to
the cell body
– Axons carry messages away
from the cell body
Draw the neuron in your notes. Be
sure to label parts!
Any message carried by a neuron is called an impulse
Neurons
An electrical 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 (space)
• Stimulates the impulse in the dendrite
of the next neuron
• Impulse moves from neuron  neuron
http://www.med.harvard.edu/publications/On_The_Brain/Volume7/Number1/images/Neuron.jpg
Two Parts
• 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
Cerebrum
•
•
•
•
•
Largest part of the brain
Thinking
Memory is stored
Movements are controlled
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
http://www.cbituk.org/GRAPHICS/brain.gif
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
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
system
has
nervous
two
major
system.
divisions.
The PNS
is made up
somatic
of 12 pairs
system
of nerves
controls
from your
voluntary
brain It
actions.
called
is
made up
cranial
of
the
nerves, and
cranial
and 31
spinal
pairs from
nerves
that
your
go
from
spinal
the
cord called
central
spinal
nervous
nerves. to
system
Spinal
your
nerves are
skeletal
made up of
muscles.
bundles of
The
sensory
autonomic
and motor
system
neurons
controls
bound
involuntary
together by
actionsconnective
those
not
tissue. For
under
this
conscious
Research
reason,
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and
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and
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the
functions.
brain at
about
the
These
same
the
two
nervous
time.
divisions,
Some
system.
nerves
along
with
Make
contain
the
central
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only
nervous
outlining
sensory
system,
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neurons,
make
medical
and
your
some
advances.
contain
body's
only motor
nervous
neurons,
system.
but most
nerves
contain
both types
of neurons.
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
FIGHT OR FLIGHT…
• This theory states that animals react to
threats with a general impulse of the nervous
system, priming the animal for fighting or
fleeing.
• Physical Response: Increased heart rate,
sweaty palms, nostrils open up and breathing
speeding up, dilated pupils, constricted blood
flow.
• FYIMales are more likely to respond to an
emergency situation with aggression (fight),
while females are more likely to flee (flight),
turn to others for help, or attempt to defuse
the situation