Transcript Introduction to the Nervous System

Biology 12
Introduction to the Nervous System
What happens to a brain during a
seizure?
 “The brain's nerve cells misfire. They either
fire when they shouldn't or don't fire when
they should. The result is a sudden, brief,
uncontrolled burst of abnormal electrical
activity in the brain. Seizures are the physical
effects of such unusual bursts of electrical
energy in the brain.”
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Neuro-Oncology Center
University of Virginia
The Nervous System
 what is the function of the nervous system?
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controls and coordinates functions throughout
the body and responds to internal and external
stimuli
The Nervous System
 what are the parts of the nervous system?
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brain
spinal cord
peripheral nerves
The Nervous System
 what are the roles of the nervous system?
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sensing
integrating
responding
The Nervous System
The Nervous System
 afferent neurons:
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aka sensory neurons
carry impulses from sensory receptors to the
central nervous system
 efferent neurons:
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aka motor neurons
carry impulses from the central nervous
system to effectors
The Nervous System
 effectors:
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muscles, organs, and glands
produce the response
The Nervous System
1.
2.
3.
4.
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a message is sent from a receptor
the nerve impulse travels along the afferent
neurons
travels to spinal cord / brain
message is then sent along efferent
neurons
response conducted by effectors
The Nervous System
 neural circuit:
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the pathway the messages travel along
 reflex arc:
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the simplest nerve pathway
a neural circuit through the spinal cord that
mediates a reflex action
involuntary
most reflexes occur without brain coordination,
because this would take too long
The Nervous System
 reflex:
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a quick, automatic response to a stimulus
 examples of reflexes:
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knee jerk
blinking
coughing and sneezing
pupillary light reflex
pulling hand from hot stove
ruler drop