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8 Cards in this Set
- Front
- Back
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types of chemical synapses
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ionotrophic receptors and metabolic receptors
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ionotrophic receptors steps
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1. neurotransmitter binds directly to the channel protein
2. channel opens immediately 3. ions flow across membrane for a brief time |
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metabolic receptor (aka G protein-coupled receptor)
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1. neurotransmitter binds to G-protein coupled receptor
2a. G protein activated 2b. the neurotransmitter then changes the metabolic rate/opens an ion channel (can either affect an ion channel or affect an enzyme which changes the metabolic rate) 3. channel opens, ions flow across the membrane for a longer period of time |
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the processes of neural transmission
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1. action potential is propagated over the presynaptic membrane
2. depolarization of the presynaptic terminal leads to influx of Ca2+ 3. Ca2+ causes vesicles to fuse with the presynaptic membrane and release the transmitter into the synaptic cleft 4. binding of the transmitter to receptor membrane opens channels, permitting ion flow and initiating an excitatory or inhibitory postsynaptic potential 5. excitatory or inhibitory postynaptic potentials spread passively over dendrites and the cell body to the axon hillock 6a. enzyme present in the extracellular space breaks down excess transmitter 6b. reuptake of the transmitter slows synaptic action and recycles subsequent transmission 7. transmitter binds to autoreceptors in the presynaptic membrane |
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temporal summation
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the summation of postsynaptic potentials that reach the axon hillock at different times, the closer in time that the potentials occur, the more complete the summation.
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spatial summation
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the summation at the axon hillock of postsynaptic potentials from across the cell body. if this summation reaches threshold, an action potential is triggered.
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excitatory postsynaptic potential (EPSP)
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a depolarizing potential in the postsynaptic neuron that is caused by excitatory presynaptic impulses. EPSPs increase the probability that an action potential will occur
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inhibitory postsynaptic potential (IPSP)
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a hyperpolarizing potential in the postysynaptic neuron that is caused by inhibitory presynaptic impulses. IPSPs decrease the probability that an action potential will occur
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