Wagner

Question 1

Axoplasmic resistance

Answer 1

increasing axon diameter decreases axoplasmic resistance and increases conduction velocity

Question 2

Myelin

Answer 2

decreases membrane capacitance and increases conduction velocity

Question 3

TTX sensitivity

Answer 3

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

Question 4

Na selectivity

Answer 4

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

Question 5

Determinants of activation

Answer 5

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

Question 6

TEA sensitivity

Answer 6

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

Question 7

Pore formation

Answer 7

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

Question 8

Na channel inactivation

Answer 8

due to isoleucine, phenylalanine, methionine residues of cytoplasmic loop

Question 9

K channel inactivation

Answer 9

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

Question 10

Ca channel inactivation

Answer 10

at S6 of repeat 1;

C-terminus there is Ca dependent inactivation

Question 11

Postsynaptic anatomical features

Answer 11

enriched w/postsynaptic receptors;

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

Question 12

Type I Synapse

Answer 12

asymmetric excitatory synapses; wide synaptic cleft; dense projections

Question 13

Type II Synapse

Answer 13

symmetric inhibitory synapses; narrow synaptic cleft; fewer dense projections

Question 14

En passant synapses

Answer 14

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

Question 15

Synaptic vesicles

Answer 15

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

Question 16

Synaptobrevin and syntaxin

Answer 16

two membrane associated proteins involved in vesicular docking and exocytotic function

Question 17

Where does vigorous exocytosis take place?

Answer 17

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

Question 18

Gs

Answer 18

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

Question 19

Gi/o

Answer 19

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

Question 20

Gq

Answer 20

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

Question 21

5HT3 receptor

Answer 21

Na+, Ca2+, K+ efflux

Question 22

GABAa receptor

Answer 22

ligand gated Cl- channel assembled from pentameric arrangement

Question 23

GABAc receptor

Answer 23

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

Question 24

Glycine receptor

Answer 24

ligand gated Cl- channel made of a and B subunits

Question 25

Nicotinic receptor

Answer 25

ligand gated mixed cation channel

Question 26

Glutamate receptor

Answer 26

3 subtypes: NMDA, AMPA and Kainate

Question 27

Fast IPSP (inhibitory postsynaptic potential)

Answer 27

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

Question 28

Slow IPSP (inhibitory postsynaptic potential)

Answer 28

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

Question 29

Fast EPSP (excitatory postsynaptic potential)

Answer 29

- 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

Question 30

Slow EPSP (excitatory postsynaptic potential)

Answer 30

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

Question 31

Presynaptic Inhibition

Answer 31

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

Question 32

Postsynaptic Facilitation

Answer 32

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

Question 33

Interactions b/n postsynaptic AMPA & NMDA receptors

Answer 33

- 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

Question 34

nAChR

Answer 34

5 subunits, long N-terminus

Question 35

Activation of nicotinic receptor

Answer 35

leads to supra threshold depolarization