Synaptic Conduction

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Synaptic Conduction

• What happens when an action potential reaches the
  axon terminals?
• Depends on the nature of synapse
• Synapse special communication region between
  two adjacent neurons or neuron and effector cell
  (i.e., muscle)

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Electrical Synapse
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Chemical Synapse
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1. action potential arrives at terminal 2.
voltage-gated Ca channels open 3. Ca triggers
exocytosis of vesicles 4. neurotransmitter is
re- leased, binds to re- ceptor 5. ligand-gated
Na or K channels open 6. neurotransmitter
broken down, taken up 7. synaptic vesicles
re- constituted 8. neurotransmitter
stored, awaits next impulse
Action potential
Synaptic vesicle
active uptake
Ca2
Ca2
voltage- gated Ca channel
docking protein
K
Postsynaptic cell
Na
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Neurotransmitters

• Acetylcholine
• Monoamines
• Norepinephrine
• Dopamine
• Serotonin
• Amino Acids
• Polypeptides
• Purines
• Gases

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Cholinergic Synapse
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Muscarinic cholinergic synapse
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Neuromuscular Junction
Nicotinic cholinergic synapse
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Transmission at an Adrenergic Synapse
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Antidepressants

• Monoamine Oxidase Inhibitors (MAOIs)
• Tricyclic Antidepressants (TCAs)
• Selective Serotonin Reuptake Inhibitors (SSRIs)
• Atypical Antidepressants

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Monoamine Oxidase Inhibitors

• Inhibit the production of the enzyme monoamine
  oxidase
• Increases amount of neurotransmitter at the
  synapses and alleviates depression
• Examples Nardil, Parnate

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Tricyclic Antidepressants

• Inhibit the reuptake of neurotransmitters at the
  synapses and alleviates depression
• Improve moods
• Stimulate appetite
• Increase activity levels
• Help people sleep
• Have fewer problems than MAOIs
• Examples Pamelor, Elavil

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Selective Serotonin Reuptake Inhibitors

• More specific than other antidepressantsblock
  the reuptake of Serotonin
• Examples Prozac, Zoloft, Paxil, Celexa

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Atypical Antidepressants

• Work in a variety of different ways to inhibit
  breakdown or reuptake of selective
  neurotransmitters
• Most similar to TCAs and SSRIs
• Examples Wellbutrin, Effexor
• Side effects dizziness, weight gain or loss,
  increased or decreased appetite, and dry mouth