Term
| Steps in Chemical Synaptic Transmission at Neuromuscular Junction |
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Definition
- AP in presynaptic terminal opens Ca2+ channels
- Ca2+ influx causes synaptic vesicles to assemble at active zone & fuse to membrane (exocytosis of NT)
- NT diffuses across synaptic cleft and binds to receptor on postsynaptic membrane
- NT binding causes K+ and Na+ channels to open, depolarizing the motor endplate to +70mV
- Endplate potential is converted to an AP, which is propagated along muscle fiber
- NT is hydrolyzed/diffuses away from synaptic cleft
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Term
| Four Differences b/t synaptic transmission in CNS and that at the Neuromuscular Junction |
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Definition
- Muscle fibers are innervated by 1 neuron; CNS fibers receive ~100 other neurons.
- Muscle fibers get only excitatory input; CNS fibers get both excitatory & inhibitory input.
- All synaptic transmission in muscle is mediated by ACh & nicotinic ACh receptors; CNS inputs are mediated by several NTs and different kinds of receptors
- Every AP in a motor neuron triggers an AP in the muscle cell; In CNS 50-100 excitatory neurons must fire together to produce an AP in the motor cell.
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Term
| What makes NMDA-type glutamate receptors "different?" |
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Definition
- control channels of high conductance permeable to Na+, K+, and Ca2+
- require glycine as a cofactor for opening
- depend on membrane voltage as well as NT for opening (blocked by Mg2+ at inadequate voltage)
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Term
| To which phase of the EPSP does the NMDA-type glutamate receptor contribute? |
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Definition
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Term
| Drugs that target GABA receptors? |
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Definition
- benzodiazopines (Valium)
- barbiturates (phenobarbital)
- alcohol
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