Lecture 19 Flashcards Preview

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Flashcards in Lecture 19 Deck (23):
1

Describe the cycle of vesicle (docking on).

Docked at plasma membrane
Primed with ATP
Ca triggered fusion & exocytosis
May/may not collapse
Clatherin mediated endocytosis
ATPase NT reloading
May/may not fuse with endosome

2

What are the three levels of vesicle pools?

Readily releasable pool = RRP = at membrane ready for release
Recycling pool
Reserve pool

3

When not in use, where are extra vesicles in the cell (either as part of recycling or reserve pool)?

Tethered to actin cytoskeleton via synapsin

4

What must happen to allow for vesicle recycling from the membrane?

Ca2+ cleared and original state restored

5

How does Ca-mediated fusion occur? (mechanism)

T-snares + V-snares
Pair --> docking --> zipper

6

How does vesicle snare dissociation occur?

NSF enzyme

7

How many alpha helices are in the T/V snare combo complex?

4

8

What are 2 noteworthy T-snares?

Syntaxin
SNAP25
Both in the target membrane

9

What is a noteworthy V snare?

VAMP (synaptobrevin)

10

What makes snare fusion Ca sensitive?

Synaptotagmin = on vesicle
"TAG into the complex"
2 C2 domains - together bind 5 Ca molecules
Binds the SNARE complex AFTER it has assembled to bring the vesicle to the plasma membrane
When active - binds the target plasma membrane, Ca binding makes it pull the 2 membranes closer together

11

What happens if you knock out synaptotagmin?

No fast vesicle release

12

What are some toxins that affect presynaptic release?

Tetanus - cleaves VAMP
Botox (botulinum toxin) - 3 types cleave each of the 3 V/T

13

What is the glutamate receptor? What ions move through the receptor?

AMPAR
Na in
K out

14

Is glutamate excitatory or inhibitory?

Excitatory - EPSP - makes sense because cations move through the receptor into the cell!

15

How is glutamate cleared from the cleft to terminate neurotransmission?

Diffusion

16

What type of post-synaptic receptor gives a fast response?

Receptors that are ion channels

17

What determines the excitatory effect of a receptor channel?

Its reversal potential

18

Do the characteristics of a single or group of channels dictate EPSP kinetics?

Single channel properties - makes sense because a single channel is the building block!

19

What ions flow through inhibitory synapses?

Cl = short circuits membrane
K = hyperpolarization

20

Where are inhibitory synapses usually located on the neuron? 3 locations.

Pre-synaptic terminal
Post synapse @ soma or axon initial segment
ALL STRONG SITES FOR INHIBITION
(Mechanism next lecture: lets excitatory signals leak out at critical junctures)

21

What signals do inhibitory synapses create?

IPSPs - hyperpolarize the cell

22

What are the 2 main inhibitory NTs? Where do they act?

Glycine = spinal cord
GABA = brain

23

What is the difference between specific and general inhibition sites?

Inhibition at the pre-synaptic side is SPECIFIC - because it silences that one synapse
Inhibition at the axon initial segments silences the entire neuron - no outgoing activity