The Action Potential

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The Action Potential
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Rising Phase

• Breaching of Threshold
• Opening of Fast Activating Sodium Channels
• Sodium Flux?

3
Falling Phase

• Closing of Sodium Channels
• Potassium Channels?
• Ion Fluxes?

4
Undershoot

• Refractory Periods
• Absolute
• Sodium Channels Inactivated
• Certain Potassium Channels remain open
• Relative
• Sodium Channels become de-inactivated

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Hodgkin Cycle
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Neurotransmitter Release
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Neurotransmitter Release
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Neurotransmitters

• Location of Synthesis
• Soma Anterograde axonal transport
• Peptides Neuropeptide Y and CCK
• Terminal Precursor enzymes in terminal
• Ach, Dopamine, 5-HT

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Ionotropic vs. Metabotropic

• Receptor and the channel are one unit
• Elicits change in membrane potential

• Receptors are not channels themselves
• Often times G-Protein linked

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