Wagner Flashcards

1
Q

Axoplasmic resistance

A

increasing axon diameter decreases axoplasmic resistance and increases conduction velocity

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2
Q

Myelin

A

decreases membrane capacitance and increases conduction velocity

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3
Q

TTX sensitivity

A

inhibits voltage-gated Na channels –> no depolarization
results in flaccid paralysis;
due to tyrosine and glutamate residue in the loop between S5 and S6 of repeat1

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4
Q

Na selectivity

A

due to collective interaction between S5, S6 and intervening loop;
critical residues include lysine of repeat III and alanine of repeat IV

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5
Q

Determinants of activation

A

arginine and lysine at every third position of S4 enables S4 to act as a voltage sensor

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6
Q

TEA sensitivity

A

inhibits voltage-gated K channels –> prolonged depolarization;
results in rigidity/tetanus;
due to consensus sequence w/n H5 loop

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7
Q

Pore formation

A

H5 loop lines the pore; S6 cytoplasmic loop linking S4 and S5 forms pore mouth

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8
Q

Na channel inactivation

A

due to isoleucine, phenylalanine, methionine residues of cytoplasmic loop

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9
Q

K channel inactivation

A

N-type (fast): inactivation ball at N terminus interacts w/cytoplasmic loop b/n S4 and S5 to form inactivation gate
C-type (slow): C-terminal undergoes conformational change

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10
Q

Ca channel inactivation

A

at S6 of repeat 1;

C-terminus there is Ca dependent inactivation

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11
Q

Postsynaptic anatomical features

A

enriched w/postsynaptic receptors;

four elements that may be contracted: dendritic spines, proximal dendrites, soma, another axon terminal

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12
Q

Type I Synapse

A

asymmetric excitatory synapses; wide synaptic cleft; dense projections

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13
Q

Type II Synapse

A

symmetric inhibitory synapses; narrow synaptic cleft; fewer dense projections

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14
Q

En passant synapses

A

intermittent presynaptic axonal swellings;
greater separation b/n presynaptic and postsynaptic elements;
no postsynaptic specializations;
transmission is diffuse and sluggish

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15
Q

Synaptic vesicles

A

derived from endosomes;
express neurotransmitter transporters;
can be filled with neurotransmitter

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16
Q

Synaptobrevin and syntaxin

A

two membrane associated proteins involved in vesicular docking and exocytotic function

17
Q

Where does vigorous exocytosis take place?

A

active zone (area of high density of voltage-gated Ca2+ channels as well as fusion and docking proteins)

18
Q

Gs

A

stimulates the adenylyl cyclase/cAMP/PKA pathway
Dopamine: D1, D5
NE/Epi: B1-3
Histamine: H2

19
Q

Gi/o

A
inhibits adenylyl cyclase/cAMP/PKA cascade and activates K channels
Dopamine: D2-4
NE/Epi: a2
Serotonin: 5-HT1
Histamine: H3
AcH: M2, M4
20
Q

Gq

A
activates PLC that acts on PIP2 to form DAG (DAG stimulates PKC, which releases intracellular Ca stores)
NE/Epi: a1
Serotonin: 5-HT2
Histamine: H1
AcH: M1, M3, M5
21
Q

5HT3 receptor

A

Na+, Ca2+, K+ efflux

22
Q

GABAa receptor

A

ligand gated Cl- channel assembled from pentameric arrangement

23
Q

GABAc receptor

A

ligand gated Cl- channel comprising different configuration of three p subunits

24
Q

Glycine receptor

A

ligand gated Cl- channel made of a and B subunits

25
Q

Nicotinic receptor

A

ligand gated mixed cation channel

26
Q

Glutamate receptor

A

3 subtypes: NMDA, AMPA and Kainate

27
Q

Fast IPSP (inhibitory postsynaptic potential)

A
  • Arises from activation of ligand-gated Cl- channels
  • At rest, produces transient hyperpolarization of postsynaptic membrane
  • Reverses polarity at Ecl-
28
Q

Slow IPSP (inhibitory postsynaptic potential)

A
  • Arises from opening of K+ channels
  • Results in hyper polarization more prolonged than the fast IPSP
  • Reverses polarity Ek
29
Q

Fast EPSP (excitatory postsynaptic potential)

A
  • Arises from activation of ligand-gated mixed cation channels
  • At rest, produces transient depolarization of postsynaptic membrane
  • Reverses polarity at 0mV, in between Eca, Ena, Ek
30
Q

Slow EPSP (excitatory postsynaptic potential)

A
  • Arises from the closing of a passive K+ channel modulated by Gq protein-coupled receptors
  • Results in long lasting depolarization
  • Reverses polarity at Ek
31
Q

Presynaptic Inhibition

A

neurotransmitter released from the upstream terminal decreases release from a downstream neuron

32
Q

Postsynaptic Facilitation

A

neurotransmitter released from the upstream terminal increases release from the downstream neuron

33
Q

Interactions b/n postsynaptic AMPA & NMDA receptors

A
  • Long term potentiation
  • NMDA receptor pore is blocked by Mg
  • Glutamate elicits an AMPA receptor-mediated depolarization and releives Mg2+ block of the NMDA receptor
  • Leads to cellular learning
34
Q

nAChR

A

5 subunits, long N-terminus

35
Q

Activation of nicotinic receptor

A

leads to supra threshold depolarization