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COGNITIVE SCIENCE 17
The Electric Brain
Part 2 Jaime A. Pineda, Ph.D.
Phases of the Action Potential
Firing threshold is the point at which the number ofactivated Na+ channels > inactivated Na+ channels
Absolute refractory period
Relative refractory period
Nodes of Ranvier
Initialsegment
Advantages of myelination
• Reduces number of ion channels
• Reduces number of Na+ / K+ pump
• Increases speed of conduction
• Reduces energy needs
Saltatory Conduction
Exocytosis
RECEPTORS
Ionotropic Metabotropic
Ionotropic
Metabotropic
Form a channel
Ionotropic Receptor
agonist
antagonist
Metabotropic Receptor
(leads to openingof channel)
Upregulation
Downregulation
Changes to Postsynaptic Receptor Density as a Function of the Amount of Neurotransmitter Released
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