Neurotransmission 1 - Kenyon Flashcards Preview

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Flashcards in Neurotransmission 1 - Kenyon Deck (107):
1

What allows ions to move between cells to create electrical transmission?

gap junctions

2

Cells connected by gap junctions are (blank) coupled

electricaly

3

Do electrically coupled cells have the same membrane potential?

Yes

4

Can action potentials travel in both directions across a synapse?

Yes!

5

Can subthreshold activity be conducted bidirectionally?

Yes!

6

In what tissues is electrical coupling of significant importance?

1. CNS neurons
2. Cardiac muscle
3. smooth muscle

7

Can a synaptic vesicle contain more than one type of neurotransmitter?

yes!

8

When an action potential is fired presynaptically, what are the three possible changes to the postsynaptic membrane potential?

1. Hyperpolarization
2. Depolarization
3. No change

9

Depolarization of presynaptic terminals causes opening of voltage gated (blank) ion channels

Ca

10

Does calcium flow in or out after activation of voltage gated channels?

IN

11

what does Ca do to the presynaptic terminal?

it causes vesicle fusion with the membrane

12

By what process are neurotransmitters released from membrane fused vesicles?

Exocytosis

13

What are the two general processes of removal of neurotransmitter from the cleft?

Glial uptake or enzymatic degradation

14

Postsynaptic current causes (blank) or (blank) postsynaptic potential that changes the excitability of the postsynaptic cell

excitatory or inhibitory

15

Is calcium necessary AND sufficient to cause neurotransmission?

YES

16

Na channel inhibitors block what step in neurotransmission? (lidocaine)

action potential

17

Lambert-Eaton and conotoxin block the influx of what ion?

Ca

18

botulinum and tetanus block what step of neurotransmission?

Vesicle release

19

Curare, benzo's, and myasthenia gravis do what to receptors?

Activate OR inactivate them

20

What two drugs block the inactivation or uptake of neurotransmitters?

Prozac and physotigmine

21

Name the five general groups of small neurotransmitters

1. ACh
2. Glutamate
3. GABA and glycine
4. Biogenic amines (Nepi, ,Epi, dopamine, serotonin, histamine)
5. ATP, ADP, AMP, adenosine

22

What are the three unconventional neurotransmitters?

1. Nitric oxide
2. Carbon monoxide
3. Endocannabinoids

23

during, synthesis of small molecule neurotransmitters, where are enzymes synthesized in the neuron?

Cell body

24

Where are small molecule neurotransmitters synthesized and packaged in the neuron?

terminal

25

Transport of enzymes and NEUROPEPTIDES from the cell body to the terminal are moved down (blank) tracks

microtubule

26

Where are neuropeptide precursors modified to produce active neuropeptides?

Terminal

27

Are small molecules or neuropeptides transported "slowly" down the axon?

small molecule

28

Once small molecules are broken down in the cleft, what happens with their components?

They are reabsorbed by the presynaptic neuron and recycled

29

What happens to the neuropeptides in the cleft after they do their job?

They diffuse out of the cleft or are degraded by proteolytic enzymes

30

What unconventional neurotransmitter has a Ca dependent enzyme in its synth?

Nitric oxide

31

What enzyme is Ca dependent for nitric oxide?

NO synthase

32

NO acts on what membrane bound effector protein?

guanylyl cyclase

33

Are unconventional neurotransmitters highly permeable?

yes!

34

What is the precursor to NO?

ARRRRRRginine

35

What is the "old school" criteria to define a neurotransmitter? (3)

1. substance must be present presynaptically in vesicles
2. Substance release must be triggered by increase in presynpatic Ca concentration
3. Specific receptors for the substance must be present postsynaptically

36

What is the "new school" criteria to define a neurotransmitter?

1.The substance can be synthesized “on demand” (unconventional neurotransmitters).
2. The substance can be synthesized “on demand” by Ca2+-activated enzymes and diffuse out of the presynaptic cell
3.Specific receptors for the substance can be present in the cytoplasm of the postsynaptic cell

37

Is ALL nuerotransmitter release Ca dependent?

YES YES YES

38

Vesicle membranes recycling is mediated by what type of endocytosis?

Clathrin-mediated endocytosis?

39

What are the three proteins needed in vesicle recycling?

1. Synaptotagmin
2. SNAREs
3. Ca channel

40

Explain "kiss and run" vesicle fusion

Only a small pore opens up between the membrane and vesicle, instead of the whole vesicle fusing, allowing for rapid vesicle recyling

41

What is quantal release of a neurotransmitter?

Vesicle fuses and dumps all its contents into the cleft

42

What effect will removal of extracellular Ca or blockage or lowering Ca entry presynaptically have on neurotransmitter release?

it will be reduced

43

Is the role of Ca in skeletal muscle the same as it is in cardiac or smooth muscle?

NO

44

Agatoxin and conotoxin act on Ca channels in what cells?

Nerve terminals and dendrites and neuroendocrine cells

45

What is the idea of co-transmission?

One neuron can release more than one type of neurotransmitter

46

What are the two factors necessary to release a neuropeptide instead of a small molecule?

1. Higher frequency of presynaptic APs
2. Higher elevation of intracellular Ca

47

Will the release of neuropeptides also stimulate the release of small molecules simultaneously?

Yes!

48

Where are small molecules ejected?

Into the synaptic cleft

49

Where are neuropeptides ejected?

They're squirted out all over the damn place

50

Ca binds at what protein during vesicle fusion?

Synaptotagmin

51

What SNARE is found on the vesicle?

synaptobrevin

52

What SNARE is found in the plasma membrane?

syntaxin

53

Is synaptotagmin on the vesicle or the plasma membrane?

Vesicle, strangely enough

54

does postsynaptic membrane PERMEABILITY change DURING synaptic transmission?

yes

55

In the Nernst equation ion concentration gradient is essentially equal to (blank)

voltage

56

the (blank) of a cell membrane to a given ion determines the contribution of that ion to the membrane potential

permeability

57

If Pk (permeability to K) is large, Em (membrane conductance) is close to (blank)

Ek (conductance of K)

58

if PNa (permeability to Na) is large, Em (membrane conductance) is close to (blank)

ENa (conductance of Na)

59

does the Nernst equation work with divalent ions?

NOOOOOPE, just monovalent (K, Na, Cl, NOT CALCIUM)

60

What physical change in the plasma membrane sets permeability to an ion?

Opening or closing of ion channels

61

Is there such a thing as gradual opening of ion channels?

No, they are either fully open or fully closed

62

Describe the steps in ion passage through an ionotropic receptor?

1. Neurotransmitter binds TO THE CHANNEL
2. Channel opesn
3. Ions flow into cell

63

Describe the steps in ion passage through a metabotropic receptor?

1. Neurotransmitter binds to a G PROTEIN
2. G protein is activated
3. G protein subunits move to an effector protein
4. Intracellular messengers from effector proteins activate the ion channel
5. Ions flow into the cell

64

If channels highly selective for Na open, what happens to PNa?

it increases!

65

Does PNa move to EQUAL ENa?

NO, it just moves TOWARD ENa

66

The larger the increase in PNa, the (blank) it becomes to ENa

closer

67

Nonselective channels move membrane potential to what value?

0 mM!!!

68

What potential is halfway between ENa and Ek?

0!!

69

the reversal potential is the (blank) potential associated with opening a particular channel

target

70

For a highly selective channel Erev is the (blank) potential of the chosen ion.

Nernst equilibrium

71

For a poorly or non-selective channel Erev will be (greater than, less, than, betwen) the Nernst equilibrium potentials of the ions that pass through the channel.

between

72

Opening a channel will shift the membrane potential towards the (blank) potential.

reversal

73

The more channels you open the closer the membrane potential will move to (blank)

Erev

74

What happens to the membrane potential of -65mV when you open nonselective channels?

It becomes less negative

75

What happens to the membrane potential of +65mV when you open nonselective channels?

It becomes more negative

76

If the membrane potential is already 0mV, what happens if you open a nonselective channel?

it stays the same!!

77

The action of a neurotransmitter drives the postsynaptic potential towad (blank) for the particular ion channels being activated

Erev (target potential)

78

The value of (blank) is determined by the relative permeability of the channels to Na+, K+, Ca2+, Cl-,

Erev

79

The main channels activated by neurotransmitters to generate receptor potentials are (blank) for monovalent cations, or (blank) for divalent ions

nonselective, selective

80

If the target potential is positive, the action potential is a (blank)

EPSP

81

If the target potential is negative, the action potential is a (blank)

IPSP

82

An EPSP makes the postsynaptic neuron (more/less) likely to fire an AP

more

83

What neurotransmitter is used for EPSPs?

glutamate! Think MSG and chinese restaurant syndrome and getting super wired!

84

What neurotransmitter is used for IPSPs?

GABA. That's why its in OTC sleep meds!

85

An IPSP makes the postsynaptic neuron (more/less) likely to fire an AP

less

86

Can an IPSP still cause a depolarization of membrane potential?

Yes, as long as the Erev remains below the threshold.

87

Ion channels nonselective for cations or selective for Ca ions mediate (blank)

EPSPs

88

Ion channels selective for K mediate (blank)

IPSPs

89

Ion channels selective for Cl mediate (blank) if Ecl is negative to threshold or (blank) if ECl is positive to threshold

1. IPSPs
2. EPSPs

90

Erev>threshold= (blank)

excitatory

91

Erev

inhibitory

92

Can a neuron sum input from thousands of inputs?

YES

93

Will one AP at one synapse cause an EPSP to reach threshold

Hellllll no!

94

Will one AP at one synapse cause an end plate potential at a nueromuscular junction to reach threshold?

Good god yes!

95

It takes (multiple/single) APs at (multiple/single) synapses for an EPSP to reach threshold

multiple, multiple

96

Can APs arrive at different times and still be summed to generate an EPSP?

NO, they have to arrive at nearly the same time

97

What is the effect of the summation of suprathreshold EPSPs and an IPSP?

the IPSP will drag the summed EPSPs down towards the target potential of the inhibitory signal

98

Is the summation of EPSPs and IPSPs linear?

NO

99

Can postsynaptic neurons signal back to the presynaptic neuron?

YES

100

What are the retrograde transmitters? (4)

1. Nitric Oxide
2. Carbon monoxide
3. Endocannabinoids
4. Prostaglandins

101

In retrograde signaling, glutamate causes an increase in (blank) influx leading to a retrograde signal

postsynaptic calcium

102

Can a neurotransmitter inhibit its own release?

YES

103

Where are the receptors located for neurotransmitter self-regulation?

on the presynaptic terminal

104

Are glia important in neurotransmission?

Yes, they are involved in clearing the synaptic cleft

105

What current type are the calcium channels used for neurotransmitter release?

PQ or N

106

What inhibits PQ calcium channels?

agotaxon

107

What inhibits N calcium channels?

conotoxin