Synaptic Transmission Flashcards

1
Q

What is the function of synapses

A

transmit info by making post-synaptic neuron excited
can delay, converge, repeat, or sustain transmission
can modify excitability of all CNS cells

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2
Q

in electrical synapse, what is allowing transmission of signal

A

gap junction

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3
Q

gap junctions in electrical synapse are important in bidirectional transmission of electrical signals b/w which cells

A

cardiac cells, smooth muscle cells, some nerve cells, and endothelial cells.

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4
Q

Draw the structure of a neuron

A

pg 8

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5
Q

what is the function of dendrites

A

receive messages from other cells

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6
Q

what is the function of the neuron cell body

A

cell’s life support center

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7
Q

what is the function of the axon hillock?

A

initiation of action potential

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8
Q

what is the function of the axon

A

passes messages away from the cell body to other neurons, muscles, or glands

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9
Q

what is nerve impulse

A

the action potential

travels down the axon

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10
Q

what is the function of the myelin sheath

A

covers axon, helps improve speed of nerve impulses

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11
Q

what is the function of terminal branches of axon

A

form junctions w/ other cells

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12
Q

chemical vs. electrical, which is more common?

A

chemical

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13
Q

describe a chemical synapse

A

always transmitted in one direction

synaptic clef separates presynaptic terminal from postsynaptic neuron

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14
Q

mitochondria are found in high density where on presynaptic neuron

A

presynaptic terminals -they need to energize the synthesis of neurotransmitteres

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15
Q

each synaptic vesicle is filled with what

A

severl thousand molecules of neurotransmitters

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16
Q

what is the synaptic vessicle made out of

A

lipid bilayer

vesicle membrane associated proteins

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17
Q

what kind of proteins are included in the synatpic vessicle

A

transporters
enzymes
proteins involved in vesicle mobilization, docking, & fusion

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18
Q

what is main function of dendritic zone and cell body

A

integrate and pass conduction of synaptic potentials to axon hillock

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19
Q

describe the release process of the vesicle from the pre-synaptic neuron

A

opening of a fusion pore between the vesicle membrane and the plasma membrane at the presynaptic terminal and the exocytosis of the vesicle contents (neurotransmitter) into the synaptic cleft

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20
Q

what part of neuron can be receptive to synaptic contact

A

cell body, dendrites, axon

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21
Q

what is another name for cell body

A

soma

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22
Q

draw a picture of Axodendritic, Axosomatic, and Axo-axonic synapses

A

pg 12

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23
Q

what is the trigger zone

A

axon hillock portion of initial segment of motor axon

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24
Q

where do axodendritic synapses occur

A

shaft or spine of a dendrite

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25
Q

what determines the effectiveness of axodendritic synapse

A

how close the synapse is to the trigger zone (axon hillock)

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26
Q

where do axosomatic synapses occur

A

on the cell body

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27
Q

what determines the effectiveness of the axosomatic synapses

A

they are automatically more effective/stronger than axodendritic b/c they are so close to the axon hillock.

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28
Q

which generate a stronger signal, axosomatic synapse or axodendritic synapse?

A

axosomatic synapse

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29
Q

where do axo-axonic synapses occur?

A

on the axon of a neuron

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30
Q

what determines the effectivness of the axo-axonic synapse?

A

b/c it’s after the trigger zone (axon hillock), it won’t have any affect on the initial signal that is released. it will indirectly affect the post-synaptic neuron b/c it will influence the amount of neurotransmitter released

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31
Q

in a motor neuron where is AP generated

A

axon hillock

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32
Q

in a sensory neuron where is AP generated

A

first node of ranvier

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33
Q

What does EPSP stand for

A

excitatory postsynaptic potential

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34
Q

What does IPSP stand for

A

inhibitory postsynaptic potential

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35
Q

can a single neuron in CNS depolarize a post-synaptic neuron?

A

no - it won’t have enough to depolarize the post-synaptic neuron

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36
Q

the threshold for firing an action potential is lowest where

A

axon hillock

37
Q

why is the threshold for firing an action potential lowest at the axon hillock

A

there is a very high density of sodium gated ion channels there

38
Q

what is function of synapses

A

one neuron will not go all the way to the CNS - need multiple stops

39
Q

what does synaptotagmin do?

A

interacts with calcium to pull vesicle

40
Q

tethering regulates the pool of vesicles available for

A

docking and release

41
Q

what is mobilization of synaptic transmission regulated by

A

tethering of vesicles to cytoskeletal elemtns within the presynaptic terminal

42
Q

tetatnus toxin will cleave

A

synaptobrevin

43
Q

describe docking

A

involves the binding of vesicle-associated proteins to presynaptic membrane proteins bringing the vesicle into close physical proximity with the release site.

44
Q

Docking positions the vesicle adjacent to the voltage gated Ca2+ channels in the active zone and near the

A

nerve terminal plasma membrane

45
Q

synaptobrevin is located on the

A

vesicle

46
Q

synaptobrevin joins with what to dock

A

SNAP25

syntaxin

47
Q

fusion is dependent on rise in what

A

Ca2+ in the axon terminal

48
Q

what is the calcium sensor

A

synatotagmin

49
Q

what is synatotagmin

A

senses calcium, it catalyzes membrane fusion

50
Q

what is the ionotropic receptor

A

ion channel

51
Q

what is the metabotropic receptor

A

second messenger, indirectly activates it

52
Q

what are examples of metabotropic receptor

A

G-proteins
cAMP
cGMP
IP3

53
Q

how can the release of neurotransmitters make changes on post-synaptic cells

A

ionotropic -immediate changes b/c t direclty activates it

metabotropic receptor - takes longer b/c it has to release other things before it works

54
Q

What does EPSP stand for

A

Excitatory Postsynaptic Potentials

55
Q

what are examples of EPSPs

A

Opening of sodium channels
Depressed conduction through chloride or potassium channels, or both.
Changes in cell metabolism to increase cell excitability, increase in number of excitatory receptors or decrease in number of inhibitory receptors.

56
Q

EPSP cause what to happen to membrane

A

depolarization

57
Q

IPSP stands for

A

Inhibitory Postsynaptic Potentials

58
Q

IPSP cause what to happen to membrane

A

hyperpolarizatoin

59
Q

IPSP prevent what from happening

A

stop it from generating action potential

60
Q

what are examples of IPSP

A

Opening of chloride channels
Opening of potassium channels
Activation of receptor enzymes that inhibit metabolic functions or increase the number of inhibitory receptors or decrease the number of excitatory receptors.

61
Q

If a graph shows line starting at -60 and then going to -40 this would be example of EPSP or IPSP

A

EPSP

62
Q

If a graph shows line starting at -60 and then going to -70 this would be example of EPSP or IPSP

A

IPSP

63
Q

what is temporal summation

A

occurs when consecutive synaptic potentials arrive at the postsynaptic cell and add together.

64
Q

draw graph showing example of temporal summation

A

pg 20

65
Q

what is spatial summation

A

two separate inputs to nerve are added simulatenously and cause depolarization twice as much as either input acting alone

66
Q

If one EPSP and one IPSP occur at the same time, what will happen
this is example of?

A

they will cancel themselves out

spatial summation

67
Q

draw graph showing example of spatial summation

A

pg 21

68
Q

need to have multiple inputs to get to

A

threshold

69
Q

where is density of voltage gated sodium channels the greatest

A

axon hillock

70
Q

look at the temporal and spatial summation graph and understand

A

pg 24

71
Q

the more area at or above the threshold the greater the

A

number of frequency of firing increases (pg 24)

72
Q

temporal summation occurs on ____ neuron

A

one

73
Q

TTX stands for

A

Tetrodotoxin

74
Q

What does TTX do

A

A virulent poison from puffer fish which blocks voltagegated Na+ channels. TTX is fatal at very low doses.

75
Q

STX stands for

A

Saxitoxin

76
Q

What does STX do

A

blocks voltage gated sodium channels

77
Q

what does procaine do

A

blocks voltage gated sodium channels

78
Q

what does lidocaine do

A

blocks voltage gated sodium channels

79
Q

nicotine mimics what

A

acetylcholine does at neuromuscular junction and get contraction

80
Q

TEA stands for

A

tetraethylammonium

81
Q

What does TEA do

A

block K+ channels

82
Q

what is result of TEA

A

increasing the time course of the action potential and shortening the relative refractory period.

83
Q

tetanus toxin acts how

A

cleaves synaptobrevin

84
Q

what is result of tetanus toxin (what does it inhibit, what are symptoms)

A

prevents release of inhibitory transmitters like glycine and GABA
muscle contractions

85
Q

botulism acts how

A

cleaving synaptobrevin, SNAP-25 or syntaxin docking proteins involved in transmitter release.

86
Q

what is result of botulism

A

inhibits ACh release from neuromuscular junctions

87
Q

slow EPSP doesn’t have any result on

A

depolarization

88
Q

draw out the summary slide starting with action potential arriving at axon terminal

A

pg 31