Chemical vs. Electrical SynapsesSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11NeuropharmacologySlide 13What determines the magnitude (amplitude) of an IPSP or EPSP?Slide 15SummaryChemical vs. Electrical Synapses•What is the difference between electrical and chemical synapses? What are the advantages of each?•How does an action potential cause the release of neurotransmitters at chemical synapses?•How does neurotransmitter release from one neuron turn into a neuronal signal in the next neuron?Electrical Synapses Why would you want an electrical synapse?Chemical SynapsesWhy would you want a chemical synapse?-65 mV-65 mVSNARE proteins coordinate the exocytosis of synaptic vesicles upon Ca2+ entryWhat would happen to synaptic transmission if we eliminated Ca2+ extracellularly?1. Synaptic transmission wouldn’t change, just the shape of the action potential would2. Synaptic transmission would be slower, but would still happen in response to an AP3. Synaptic transmission would be blocked entirelyWhat would happen if we increased the number of V-gated Ca2+ channels presynaptically?1. Less transmitter would be released2. More transmitter would be released3. The presynaptic terminal would be more depolarized, but there would be no change in the amount of transmitter releasedNeurotransmittersCriteria for being classified as a neurotransmitter–manufactured in neurons–released by neurons in response to activity–receptors–mechanism of terminationdiffusion, degradation, reuptakeNeurotransmittersGlutamate- major excitatory neurotransmitter in the brainGABA- major inhibitory neurotransmitter in the brainReceptors2 Main Types:1. Transmitter-gated2. MetabotropicNeuropharmacologyAntagonistAgonistWhich do you think is most important in determining whether a synapse is excitatory or inhibitory?1. The neurotransmitter2. The amount of extracellular Ca2+ 3. The receptor4. The size of the synaptic clef5. The SNARE proteins that are present on the vesicles-65 mV-65 mVWhat determines the magnitude (amplitude) of an IPSP or EPSP?How could you tell the difference between a chemical and electrical synapse?Summary•Electrical synapses use gap junctions to directly conduct electrical signals from one neuron to the next•Chemical synapses release neurotransmitters in response to a presynaptic action potential, which is then converted into a postsynaptic electrical signal by receptor binding–The definition of neurotransmitters have changed over time–The main neurotransmitters of the CNS are GABA and glutamate–Receptors can be either metabotropic or ionotropic–Agonists and antagonists alter the activity of receptors by activating them or blocking neurotransmitter effects,