The Electrical Brain - Part 2

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COGNITIVE SCIENCE 17 The Electric
Brain Part 2 Jaime A. Pineda, Ph.D.
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Phases of the Action Potential
Absolute
refractory period
Relative refractory period
Firing threshold is the point at which the number
of activated Na channels gt inactivated Na
channels
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Initial segment

Nodes of Ranvier
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Advantages of myelination

• Reduces number of ion channels
• Reduces number of Na / K pump
• Increases speed of conduction
• Reduces energy needs

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Saltatory Conduction
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Exocytosis
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RECEPTORS
Ionotropic
Metabotropic
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Ionotropic
Form a channel


Metabotropic


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Ionotropic Receptor
agonist
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antagonist
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Metabotropic Receptor
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(leads to opening of channel)
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Changes to Postsynaptic Receptor Density as a
Function of the Amount of
Neurotransmitter Released
Upregulation
Downregulation