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16 Cards in this Set
- Front
- Back
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why is the neuromuscular junction the stereotypical synapse?
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transmission process is better defined than autonomic neurons and smooth/cardiac muscle
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what is synaptic delay?
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the amount of time taken for the synaptic mediator to be released & act on the postysynaptic membrane
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what implications does having lots of synapses vs one have on neurotransmission?
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many connections slow down transmission due to synaptic delay
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how is EPSP all or nothing?
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it's not at all, is a summation of all inputs
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how would influx of Cl- affect the membrane potential?
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membrane potential would increase
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how does the membrane potential fluctuate?
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constant interplay of excitatory & inhibitory activity produces a fluctuating membrane potential
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what regulates the fluctuating membrane potential?
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the soma
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what is the initial segment?
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portion of motor neuron with lowest threshhold for producution of full fledged action potential
the portion of axin at & just beyond the axon hillock unmyelinated |
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what is direct versus indirect inhibition?
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postsynaptic inhibition is direct (nil influence of presynaptic neuron)
vs indirect - due to previous postsynaptic (eg refractory period) |
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what is presynaptic inhibition?
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when a neuron terminal is on an excitatory ending rather than straight onto the motor terminal
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what neurotransmitter was the first to be identified in presynaptic inhibition?
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GABA
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how does presynaptic inhibition & facilitation differ in terms of the action potential?
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inhibition shortens the action potential whereas facilitation lengthens it
inhibition tends to decrease Ca++ influx where facilitation increases it |
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what are interneurons & are they typically excitatory or inhibitory?
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neuron connecting afferent & efferent neurons
cell bodies always in CNS typically inhibitory, run on GABA/glycine |
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how do EPSPs differ from IPSPs in terms of polarization of the membrane & ions involved?
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EPSP: depolarization of postsynaptic cell by influx of Na+ or Ca++ ion channels
IPSP: hyperpolarization of the postsynaptic cell, can be produced by increase in Cl- transport |
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how do slow EPSPs/IPSPs differ ionically from regular EPSP/IPSP?
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slow EPSP involve decrease in K+ conductance; slow IPSP involve increase in K+ conductance
vs the Na+/Ca++/Cl- seen in regular ones |
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where are slow EPSPs/IPSPs seen? (3)
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autonomic ganglia
cardiac/smooth muscle cortical neurons |
