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57 Cards in this Set
- Front
- Back
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What allows cells to be electrically coupled?
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Gap junctions
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What substances can pass through gap junctions?
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Ion
Molecules <1000 in MW |
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What allows large groups of neurons to have synchronized activity?
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Gap junctions
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What causes vesicles to fuse with plasma membrane and release their neurotransmitters?
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Calcium channels in the terminal portion of the axon are opened causing snare proteins to bind and fuse the vesicles.
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What drug can block the propagation of the action potential?
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lidocaine (local anesthetic)
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What drug can block the calcium influx in the axon terminal?
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conotoxin
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What drug can block the release of neurotransmitter vesicles?
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BoTX
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What drug can block the nicotinic receptor on the post-synaptic neuron?
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curare
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What drug can block the uptake of Serotonin (block inactivation)?
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Re-uptake inhibitors
physostigmine prozac |
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What is the role of voltage-gated calcium channels on the presynaptic membrane?
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Allows depolarization to cause influx of calcium to trigger the fusing of vesicles.
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What happens in the axon terminal if extracellular calcium is removed or the voltage-gated calcium channels are blocked?
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No release of NT.
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What is Co-transmission?
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the release of many NT by a singe neuron
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Which vesicles in the axon terminal will fuse with low frequency stimulation?
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clear core vesicles with small-molecule neurotransmitters
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Which vesicles in the axon terminal will fuse with a high frequency stimulation?
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Clear core vesicles with small molecule NT
Large dense core vesicles with neuropeptides |
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Where do clear core and large dense vesicles fuse?
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Clear core vesicles fuse and release NTs into the synaptic cleft
Large dense vesicles fuse and release NTs into the ECF (lateral to the cleft). |
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What is varied in low and high frequency stimulation?
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The area of high calcium concentration in the axon terminal
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Vesicles are retrieved from the plasma membrane by what process?
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Endocytosis
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Once vesicles are retrieved, vesicles are returned to what organelle?
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The endosome
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What is kiss-and-run exocytosis?
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Incomplete fusion.
Vesicle is able to release its NT load and bud off of the plasma membrane all in one action. |
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Which vesicles are able to kiss-and-run?
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Competent ones
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What three proteins are most important in NT release?
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Snares
Synaptotagmin Calcium channel |
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What protein functions as the calcium sensor?
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Synaptoagmin
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What Snares are involved in vesicle docking?
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Synaptobrevin
Syntaxin SNAP-25 |
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What is the function of SNAP-25?
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to regulate the assembly of the vesicle SNARE and the membrance SNARE
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What SNARE is located on the vesicle?
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Synaptobrevin
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What SNARE is located on the cell membrane?
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Syntaxin
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What ion catalyzes membrane fusion after vesicle docking?
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Calcium
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What protein does calcium bind to initiate vesicle fusion?
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synaptotagmin
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What is Ek?
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-90mV
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What is ENa?
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+90mV
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What is ECl?
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-88 to -35mV
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What is ECa?
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+100mV
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What is the extracellular Na concentration?
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145
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What is the intracellular K concentration?
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140
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Where is Cl most concentrated, inside or outside the cell?
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Extracellular, 110
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Where is Ca most concentrated, inside or outside the cell?
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Extracellular
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The contribution of a ion gradient to the membrane potential is weighted by what factor?
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the ions permeability
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How is permeability altered?
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by opening and closing ion channels
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What type of channel would allow both Na and K ions through?
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a non-selective channel
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If non-selective Na/K channels open, what happens to the membrane potential?
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Moved to a potential in between the EK and ENa.
Happens to be zero. |
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What is Erev?
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The reversal potential, a target potential associated with a particular channel.
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What is the Erev for a highly selective channel?
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The Nernst equilibrium potential of the ion.
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What is the Erev for a non-selective channel?
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A potential in between the Nernst potential of the ions that pass through the channel.
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When any channel is opened, towards what value will the membrane potential head?
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towards Erev
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What is the action of a NT on the postsynaptic potential?
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Shifts potential towards the reversal potential (target potential) for the activated ion channels.
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Which ion channels are targeted by NTs to generate receptor potentials?
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Cl
Ca Nonselective monovalent cations |
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Describe what happens if Erev is positive to threshold.
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If target potential is positive to threshold, the event is an excitatory postsynaptic potential (EPSP)
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Can an EPSP caused by a single axon reach Erev or threshold?
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Typically no, summation is needed to propagate an action potential onto a postsynaptic neuron
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Describe what happens when Erev is negative to threshold, but positive to resting potential.
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Nothing.
Inhibitory postsynaptic potential (IPSP). Cell will never reach threshold. Membrane will stabilize negative to threshold despite being depolarizing. |
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Describe what happens when Erev is negative to threshold and negative to resting potential.
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Inhibitory postsynaptic potential (IPSP)
Cell will become hyperpolarized |
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Generally, which ion channels mediate EPSPs (Erev + to threshold)?
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Ca channels (Erev=+100)
nonselective cation channels (Erev=0) |
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Generally, which ion channels mediate IPSPs (Erev - to threshold)?
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K channels
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Will Cl ion channels mediate EPSPs or IPSPs?
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Both
IPSPs when Erev= -88 EPSPs when Erev= -35 (early development) |
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What two factors are important to summation of inputs by a neuron?
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Timing and location
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Explain the difference between an endplate potential and IPSPs/EPSPs.
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At the NMJ, one AP evokes a EPP, which triggers one AP in the muscle
IPSPs and EPSP only increase or decrease the likelihood that the postsynaptic neuron will fire or not. |
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What four substances are known retrograde transmitters from postsynaptic neuron to presynaptic neuron?
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NO
CO Cannabinoids Prostaglandins |
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The presynaptic terminal can be regulated. How is neurotransmitter release inhibited or facilitated?
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Common for a NT to inhibit its own release
Can be mediated by another presynaptic neuron that will inhibit or facilitate |
