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Intro to Neuro - Test 1 > Synaptic Transmission > Flashcards

Synaptic Transmission Flashcards

1
Q

what is a neurotransmitter

A

chemical

primary means of communication b/w cells

allows neurons to communicate with one another

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2
Q

what is a synapse

A

point of contact

where one neuron comes in contact with another neuron

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3
Q

presynaptic side

A

axonal terminal

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4
Q

post synaptic side

A

may be another dendrite or soma of another neuron

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5
Q

synaptic cleft

A

space b/w the 2 sides

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6
Q

synaptic transmission

A

transfer of info across the synapse

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7
Q

how are NT synthesize

A

by the neuron

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8
Q

where are NT stored

A

the vesicles at the nerve terminal

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9
Q

what is the post synaptic side (specifically)

A

a protein

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10
Q

what happens when the NT crosses the synapse and binds w/ the post synaptic receptors

A

protein changes shape

alters the fxn of the receiving neuron

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11
Q

kinds of synapses

A

axondendritic

axosomatic

axoaxonic

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12
Q

types of synapses

A

electrical

chemical

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13
Q

electrical synapse

A

not very common in the NS

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14
Q

chemical synapse

A

very common in the NS

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15
Q

how do electrical synapses run

A

can act in either direction

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16
Q

passage –> electrical synapse

A

there is a passage of electrical current secondary to cell membranes of neurons communicating w/ one another
–>occurs b/c of low resistance gap jxns

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17
Q

chow to chemical synapses run

A

impulse only has ability to travel in one direction

release of NT from presynaptic side –> membrane of the postsynaptic side

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18
Q

steps 1-4 of impulse travel

A
  1. arrival of action potential, Ca+ channels opened
  2. Ca+ influx into presynaptic term
  3. Ca+ acts as intracellular messenger stimulating synaptic vesicles to release NT
  4. Ca++ removed from the synaptic knob by mitochondria or calcium-pumps
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19
Q

steps 5-7 of impulse travel

A
  1. NT diffuses across synaptic cleft and binds to receptor on postsynaptic membrane
  2. receptor changes shape of ion channel opening it and changing membrane potential
  3. NT is quickly destroyed by enzymes or taken back up by astrocytes or presynaptic membrane
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20
Q

types of chemical synapses

A

excitatory chemical synapses

inhibitory chemical synapses

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21
Q

excitatory chemical synapses cause

A

a depolarizing graded potential in the postsynaptic cell

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22
Q

EPSP

A

excitatory postsynaptic potential

moves the membrane potential towards threshold

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23
Q

what kind of channels do excitatory chemical synapses use

A

only chemically gated channels

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24
Q

do postsynaptic membranes generate APs?

A

no

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25
Q

what do EPSPs do to resting membrane potential

A

bring RMP closer to threshold

closer to an AP

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26
Q

what do inhibitory chemical synapses cause

A

either hyperpolarizing graded potential or a stabilization of the resting membrane potential in the postsynaptic cell

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27
Q

IPSP

A

inhibitory postsynaptic potentials

move the membrane potential away from threshold

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28
Q

what does stabilization of the membrane potential prevent

A

EPSPs from being created in the postsynaptic cell

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29
Q

summation

A

a single EPSP CANNOT initiate an AP

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30
Q

what must EPSPs do to bring membrane potential to threshold at the axon

A

must summate

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31
Q

2 types of summation

A

temporal

spatial

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32
Q

temporal summation

A

postsynaptic potentials are generated at a high frequency

sequential postsynaptic potentials “piggyback” one another

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33
Q

spatial summation

A

multiple postsynaptic potentials are generated at different locations at the same time and converge at the axon

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34
Q

neurons are made up of

A

cell body

dendrites

axons

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35
Q

dendrites

A

input structure

receive inputs from other neurons

relay them to the cell body

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36
Q

axons

A

output structure

a fiber that carries messages (spikes) from the cell to dendrites of other neurons

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37
Q

what do neurons do

A

conduct info

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38
Q

what do action potentials move

A

down the axon

39
Q

what propagates the message down the neuron

A

the cell membrane

40
Q

what happens as the AP moves down the neuron

A

does not diminish in intensity over a distance

signal is fixed

duration is fixed

info is coded

41
Q

info coded in an AP

A

frequency of firing

how many neurons of the same nerve are firing together

42
Q

what does the cell membrane do

A

surrounds the neuron

43
Q

what are the main building blocks of the cell membrane

A

phospholipids

44
Q

the cell membrane is

A

semipermeable

regulator

45
Q

how is the cell membrane a regulator

A

determines the movement of ions into and out of the neuron

46
Q

how are ions distributed across the membrane

A

unevenly

47
Q

what does the sodium potassium pump do

A

develops an electrical gradient with a greater positive charge outside of the cell membrane

48
Q

what is the key determinant of neuronal fxn

A

permeability of potassium channels

49
Q

what is an ion channel

A

cell membrane proteins that pass ions in and out of the cell

50
Q

2 types of ion channels

A

voltage-gated ion channels

chemical-gated ion channels

51
Q

voltage-gated ion channels

A

gates are regulated by membrane voltage

52
Q

chemical gated ion channels

A

also called receptors

gates are regulated by NTs

53
Q

depolarization

A

increase in permeability of the Na+ channels

inward Na+ current

decrease in internal negativity

54
Q

hyperpolarization

A

increase in permeability of the K+ channels

outward K+ current

increased internal negativity

55
Q

the membrane is mostly

A

impermeable

forms a barrier to many proteins, molecules and other ions dissolved in the intracellular and extracellular fluids

56
Q

what is the membrane selectively permeable to

A

sodium

potassium

chlorine

57
Q

what is the most permeable

A

K+

58
Q

what is the least permeable

A

Na+

59
Q

RMP

A

-65 mv

critical to understanding cellular behavior

60
Q

when does EPSP occur

A

depolarization

61
Q

when does IPSP occur

A

hyperpolarization

62
Q

what is depolarization and hyperpolarization

A

transient changes in the membrane potential

63
Q

what is temporal summation dependent upon

A

amount of time in b/w receiving EPSPs and IPSPs

64
Q

what is spatial summation dependent on

A

distance b/w the incoming IPSPs and EPSPs

65
Q

when does an AP begin

A

if the graded potentials add up to threshold

66
Q

threshold depolarization

A

when the summation of all the incoming info to the dendrites and the soma reaches a critical level

Na+ channels at the hillock open

67
Q

Na+ channels opening –> action potential

A

rush of positive ions into the axon cause the membrane potential to become positive

the change and the subsequent reversal of the change (repolarization) is the actual AP

resting levels become more negative than normal or hyperpolarized

68
Q

what happens to the axon hillock during the AP

A

less responsive to other stimuli

69
Q

what happens to Na+ channels during an AP

A

inactivated for a period of time after the peak Na+ conductance

this is the absolute refractory period

70
Q

what is the absolute refractory period

A

where no stimuli can impact on the axon hillock

71
Q

an action potential is a _______ event

A

all or nothing

there is no thing as a strong or weak AP

72
Q

are there summations of APs?

A

no

however there could be increases in firing frequency of the APs

73
Q

what are APs throughout the course of transmission

A

consistent in amplitude and duration

74
Q

throughout depolarization

A

Na+ continues to rush inside until the AP reaches its peak

–> Na+ gates then close

75
Q

what is depolarization is not great enough to reach threshold

A

an AP is not produced

an impulse is not produced

76
Q

where does an AP go after the axon hillock

A

axon terminal

77
Q

how does the AP go from the hillock to the terminal

A

wave like fashion

change in RMP occurs down the axon

78
Q

what is speed or conduction velocity of an AP dependent on

A

diameter of the axon

presence of myeline sheath

79
Q

what does a myelin sheath do

A

increases conduction velocity

80
Q

myeline

A

specialized glial cells that surround the axon

schwann cells = pns

oligodendrocytes = cns

81
Q

what does myeline surround

A

axon in segments

82
Q

nodes of ranvier

A

where there is no myeline

saltatory conduction

83
Q

saltatory conduction

A

AP “jumps” from one node to the next

84
Q

passive conduction

A

will ensure that adjacent membrane depolarized

so AP “travels” down the axon

but transmission by continuous APs is relatively slow and energy consuming

85
Q

myelination provides

A

saltatory conduction

86
Q

how do impulses travel down neurons

A

very rapidly

87
Q

what does the presence of myeline do

A

greatly increases the velocity at which impulses are conducted along the axon of a neuron

88
Q

unmyelinated fibers

A

entire axon membrane is exposed

impulse conduction is slower

89
Q

when are NT released

A

into the synaptic cleft in response to the AP

90
Q

what do the NT do

A

bind to the postsynaptic receptors

cause IPSPs or EPSPs on the opposite side

91
Q

NT are either

A

recycled by the presynaptic terminal

degraded by enzymes in the synaptic cleft

passive diffusion

absorbed by glial cells

92
Q

gap jxn

A

membranes of joining cell membranes line up

when activity occurs on one side, it occurs on the other side as well

93
Q

parasynaptic neurotransmission

A

NTs released form the axon terminal diffuse into the extracellular space before encountering its postsynaptic target

Intro to Neuro - Test 1 (22 decks)

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