1. 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)

2. Electrical Synapse

3. Chemical Synapse

4. Action potential Synaptic vesicle Ca 2+ docking protein voltage- gated Ca channel Postsynaptic cell Na + K+K+ active uptake 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

5. Neurotransmitters Acetylcholine Monoamines –Norepinephrine –Dopamine –Serotonin Amino Acids Polypeptides Purines Gases

7. Cholinergic Synapse

8. acetylcholine muscarine (agonist) Muscarinic cholinergic synapse X atropine (antagonist)

9. Neuromuscular Junction acetylcholine acetylcholinesterase nicotine (agonist) Nicotinic cholinergic synapse X curare (antagonist) X botulinum toxin

10. Transmission at an Adrenergic Synapse

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

12. Monoamine Oxidase Inhibitors Inhibit the production of the enzyme monoamine oxidase Increases amount of neurotransmitter at the synapses and alleviates depression Examples: Nardil, Parnate

13. 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

14. Selective Serotonin Reuptake Inhibitors More specific than other antidepressants— block the reuptake of Serotonin Examples: Prozac, Zoloft, Paxil, Celexa

15. 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