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Flashcards in Synaptic transmission Lec06 Deck (54)
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1
Q

EPSPs increase the probability for an action potential to be generated because they let _____ into the cell body depolarizing the cell. 

A

sodium

2
Q

IPSPs decrease the probability for AP by

A

letting K out or chlorine in

3
Q

direction of electrical synapses

A

bidirectional

4
Q

electrical synapses are connected via 

A

gap junctions (made of connexins)

5
Q

what kind of pores do electrical synapses have? what do they let in

A

 very large pores for unselective ion diffusion

6
Q

what triggers vesicle fusion?

A

influx of ca through voltage gated ca channels

7
Q

what happens if you have no Ca voltage gated channels

A

no NT release

8
Q

what happens if you ↓ external [Ca] 

A

 ↓ # of vesicles = ↓ postsynaptic potential

9
Q

Ionotropic receptors - ligand-gated ion channels respond in ____ 

A

msec

10
Q

Metabotropic receptors - G-protein-linked receptors that respond in ___

A

sec/min (growth factor recpeotrs take even longer)

11
Q

how does inactivation of chemical nt take place 

A

 via reuptake, glial uptake, diffusion, or enzymatic breakdown

12
Q

what are the advantages of chemical synapses 

A

directionality, amplification, plasticity, summation

13
Q

what is facilitation 

A

 short-term synaptic plasticity

14
Q

what does facilitation involve?  what does it result in?

A

 multiple action potentials in a short time (<50 msec) = ↑↑ in synaptic strength

15
Q

describe the 2nd epsp after facilitation 

A

2nd EPSP larger than the 1st  because Ca clearance is slower than Ca entry into cell

16
Q

how large are small molecule nt

A

50 nm diameter

17
Q

how are small molecule NT stored?

A

in clear vesicles

18
Q

some ___ are docked at active zones

A

small molecule nt

19
Q

docked small molecule nt are released by 

A

local ca influx

20
Q

how are neuropeptides stored?

A

dense core vesicles

21
Q

what is required for neuropeptide release? 

A

high frequency stimulation

22
Q

Vesicle release is quantal/discrete: each vesicle = 

A

1 mini end plate potential

23
Q

how do miniend plate potentials cause depolarization? 

A

Many MEPPs make up the endplate potential, EPP, causing depolarization

24
Q

how can you get larger mini end plate potentials?

A

more ach or more veiscles

25
Q

cable theory

A

neuron changes in synapse potential decrease with time and space

26
Q

___ and ___ determine probability of an action potential due to leakage

A

Temporal and spatial summation

27
Q

EPSP & IPSP amplitude & direction depend on 

A

ion permeability and membrane voltage

28
Q

NMDA is slower, Mg-blocked, but allows ___

A

Ca entry

29
Q

GABA__ receptors are ligand-gated channels

A

 A

30
Q

GABA A receptors make __ with CL- ions

A

fast ipsp

31
Q

GABA A receptors have ___ subunits

A

5

32
Q

what increases the GABA A channel open time

A

a barbituate + gaba (increases the channel open time)

33
Q

GABA __ receptor are g protein linked and slower

A

B

34
Q

how many synapses does each neuron integrate ifnormation from?

A

multiple

35
Q

what are the 4 criteria for chemical NTs?

A

1) present in presynaptic terminal.
2) released in response to stimulation – release must be Ca2+ dependent.
3) specific receptors for the neurotransmitter must be present on the postsynaptic cell.
4) mechanism to inactivate neurotransmitter must be present (reuptake, enzymatic breakdown).

36
Q

what type of flow occurs through gap junctions in electrical synapses

A

passive flow

37
Q

how common are electrical synapses?

A

they are present in cns but less common than electrical synapses

38
Q

 brainstem neurons that regulate breathing are synchronized by 

A

electrical synapses.

39
Q

chemical syanspes provide potentiation for

A

1. excitation and inhbiiton

2. plasticity and remodeling

40
Q

what drives Ca into the presynatpic membrane

A

concentration gradient (more ca outside)

electrical gradient 

41
Q

what does facilitation result from?

A

prolonged elevation of presynaptic Ca

42
Q

Synaptic facilitation is a rapid increase in ___

A

synaptic strength

43
Q

. Facilitation is not observed if __

A

two APs arrive far apart in time 

44
Q

how many chemical transmitters can a single neuron release?

A

many

45
Q

what is the range of time courses of chemical transmitters?

A

msec to days

46
Q

trnasport of neuropetide vesicles is dependent on ___

A

ATP

47
Q

what is the postsynaptic density

A

an electron dense area with many receptors in the postsynaptic target cell

48
Q

 The MEPPs result from the discharge of the contents of 

A

a single synaptic vesicle

49
Q

post synaptic potentials resutl from 

A

conductance changes to

50
Q

synaptic potentials are passive events that become progressively smaller at

A

greater distances ro

51
Q

why dont dendrites transmit AP?

A

1. they do not contain many Na+ channels

2. their thresholds for excitation are too high.

52
Q

what does capable theory take into account 

A

1. membrane capacitance

2. embrane resistance

3. longitudinal cytoplasmic resistance between different parts of the neuron

53
Q

glutamate binding to ampa and nmda exhibits distinct

A

1. kinetics

2. pharmacologic sensitivites

3. target cell effects

54
Q

interposition of a ____ in a neuronal circuit can prevent overactity in the cns

A

inhbiitior synapse