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YEAR 3 NEURO > PHYSIOLOGY - Neurones, nerve conduction and synaptic transmission > Flashcards

PHYSIOLOGY - Neurones, nerve conduction and synaptic transmission Flashcards

1
Q

what is the function of a dendrite

A

receives input from other neurones and conveys to soma

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2
Q

what are the 2 functions of the soma

A
  • cell body - synthetic and metabolic centre - contains ribosomes, mitochondria and ER
  • integrates incoming electrical signals and conducts them passively to the axon hillock
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3
Q

what is the site of initiation of all or none action potential

A

axon hillock and initial segment

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4
Q

what is the function of the axon

A

conducts output signals as APs to the presynaptic terminal

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5
Q

how are materials transported between the soma and the presynaptic terminal

A

axonal transport

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6
Q

what are the 2 types of axonal transport

A

anterograde - body to PST

retrograde - PST to body

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7
Q

which type of axonal transport do viruses exploit

A

retrograde

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8
Q

give 3 examples of viruses that exploit retrograde axonal transport to infect neurones

A

polio
rabies
herpes

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9
Q

what is a synapse

A

point of chemical communication between neurones / other cells

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10
Q

what are the 4 possible polarities of neurones and what do they entail

A

unipolar - one neurite
pseudounipolar - one neurite that bifurcates
bipolar - 2 neurites
multipolar - 3 or more neurites

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11
Q

give an examples of a unipolar neuron

A

peripheral autonomic nerve

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12
Q

give an examples of a pseudounipolar neuron

A

dorsal root ganglion neurone

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13
Q

give an examples of a bipolar neuron

A

retinal bipolar neurone

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14
Q

give an examples of a multipolar neurone

A

lower motor neuron

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15
Q

what is meant by golgi type I

A

long axon

golgi type II is short axon

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16
Q

what are the 4 functional regions of a neurone

A

input
integrative
conductile
output

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17
Q

K+ ions and organic anions are typically found at higher concentrations inside / outside the cell

A

inside

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18
Q

Na + and Cl- are typically found at higher concentrations inside / outside the cell

A

outside

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19
Q

at rest, the cell membrane is most permeable to which ion

A

K+

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20
Q

which ion has the biggest influence on the resting membrane potential

A

K+

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21
Q

what maintains the concentration gradients at rest

A

Na+/K+/ATPase via active transport

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22
Q

depolarisation causes what ion channels to open and in which direction do these ions move

A

voltage gated Na+ channels

causing Na+ influx

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23
Q

what is meant by all or nothing

A

AP will only occur if a threshold is met, and if this threshold is met there will be a maximal response

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24
Q

once the cell has been depolarised the ___ channels close and the __ channels open causes what ions to move where

A

Na+ channels close and K+ channels open

causing K+ ion efflux –> repolarisation

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25
Q

is Na/K/ATPase involved in repolarisation

A

no

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26
Q

what often occurs with repolarisation

A

undershoot of RMP making membrane potential more negative

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27
Q

what is meant by the absolute refractory period

A

once the sodium channels close after an AP they enter an inactive state when they can’t be reopened regardless of the membrane potential

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28
Q

what is meant by the relative refractory period

A

the Na ions slowly come out of inactivation during which time they may be excited with stimuli stronger than one normally needed

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29
Q

the refractory period ensures ….

A

unidirectional flow of AP

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30
Q

what is the overshoot

A

brief period when polarity is reversed to inside positive

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31
Q

what is the resting membrane potential of a neurone

A
  • 70
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32
Q

why do passive signals not spread far from their site of origin

A

current loss across the membrane accompanied by a reduced change in potential - leaky membrane

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33
Q

what is ohm’s law

A

V= IR

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34
Q

for a given current, the potential change increases/decreases linearly with membrane resistance

A

increases

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35
Q

what is the equation for length constant (lambda)

A

( rm / ri )^0.5

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36
Q

the ____ the length constant, the further the local current spread and so the higher the AP conduction velocity

A

longer

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37
Q

the _____ the length constant, the higher the AP conduction velocity

A

longer

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38
Q

give 2 ways in which the passive current spread could be increased

A

decrease axial resistance

increase membrane resistance

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39
Q

how could axial resistance be reduced

A

increase diameter of axon

40
Q

how could membrane resistance be increased

A

insulation - myelin sheath

41
Q

what cells provide myelin in the CNS

A

oligodendrocytes

42
Q

what cells provide myelin in the PNS

A

Schwann cells

43
Q

schwann cells and oligodendrocytes are both types of ____ cells

A

macroglial cells

44
Q

true/false

a single schwann cell can insulate up to 50 axons

A

false

an oligodendrocyte can, but a schwann cell can only insulate 1 axon

45
Q

myelin increases/decreases membrane capacitance

A

decreases

46
Q

what is saltatory conduction

A

AP jumps from one node of ranvier to the next

47
Q

what clusters are the nodes of ranvier

A

voltage activated Na+ channels

48
Q

give 2 disorders that would cause slowing or cessation of nerve conduction

A

MS (CNS)

Guillian Barre Syndrome (PNS)

49
Q

what are the 8 steps in chemical neurotransmission at the synapse

A 
uptake of precursor 
synthesis of transmitter
storage of transmitter 
depolarisation by AP
Ca influx through VGCC
Ca induced release of transmitter (exocytosis)
receptor activation
enzyme mediated inactivation of transmitter or reuptake of transmitter
50
Q

what holds the pre and post synaptic membranes together

A

matrix of fibrous extracellular protein within cleft

51
Q

where are the active zones and what are they

A

pre-synaptic membranes

vesicles cluster around them and opposite to neurotransmitter receptors

52
Q

what are the 3 types of synapse and what is the most common

A

axodendritic - most common
axosomatic
axoaxonic

53
Q

what is the main excitatory transmitter in the CNS

A

glutamate

54
Q

glutamate activates the post-synaptic, ____ selective (__), ___tropic glutamate receptors generating a local, graded, excitatory response

A 
cation selective (Na+)
ionotropic
55
Q

excitatory stimulation causes ____

A

depolarisation

56
Q

glutamate generates a ...

A

EPSP

excitatory post synaptic potential

57
Q

what are the main inhibitory transmitters in the CNS

A

GABA or glycine

58
Q

what is the actual name of GABA

A

gamma - aminobutyric acid

59
Q

GABA/glycine activate a postsynaptic, ____ selective (__), ___tropic GABAa/glycine receptors generating a local, graded inhibitory response

A 
anion selective (Cl-)
ionotropic
60
Q

inhibitory stimulation causes ____

A

hyperpolarisation

61
Q

GABA/Glycine generate a ...

A

IPSP

inhibitory post synaptic potential

62
Q

what are the 3 main amino acid neurotransmitters in the CNS

A

glutamate
glycine
GABA

63
Q

what is spatial summation

A

how many of each type of stimulation (inhibitory/excitatory) a neuron is receiving - many inputs converge upon a neurone to determine its output

64
Q

what is temporal summation

A

tempo
how often a neuron is receiving stimulation of each type - a single input may modulate output by variation in AP frequency of that input

65
Q

name 4 amine neurotransmitters

A

dopamine
histamine
noradrenaline (NA)
serotonin (5-HT)

66
Q

Ach, amino acids and amines are released from ___

A

synaptic vesicles

67
Q

peptides are released from ____

A

secretory vesicles

68
Q

what neurotransmitters can activate ionotropic ligand gated channels

A 
glutamate
gaba
glycine 
Ach
5-HT
69
Q

all except ___ can activate metabotropic G protein coupled receptors

A

glycine

70
Q

ionotropic/metabotropic receptors mediate slow neurotransmission

A

metabotropic

71
Q

ionotropic receptors mediate ___ neurotransmission

A

fast

72
Q

what receptors use direct gating

A

ionotropic ligand gated ion channels

73
Q

how do metabotropic receptors use indirect gating

A

neurotransmitter acts on a G-protein complex that is distinct from the ion channel it controls

74
Q

how do ionotropic receptors use direct gating

A

receptor is an integral part of the channel it controls

75
Q

cholinergic synaptic transmission in autonomic ganglia uses both direct and indirect transmitter action.
Fast EPSP is due to ionotropic ____ Ach receptors - channels conduct __ and __

A

nicotinic

Na+ and K+

76
Q

cholinergic synaptic transmission in autonomic ganglia uses both direct and indirect transmitter action.
slow EPSP is due to metabotropic ____ Ach receptors - ACh closes a __ channel

A

muscarinic

K+ (m-type)

77
Q

true/false

glutamate has inhibitory function aswell

A

true - via metabotropic glutamate receptors

78
Q

how can ionotropic glutamate receptors be classified

A

response to non-endogenous agonists that mimic glutamate

79
Q

which receptors bind the agonist that mimics glutamate

A

non-NMDA receptors

80
Q

give 2 examples of exogenous agonists that mimic glutamate and bind to non-NMDA receptors

A

kainite or AMPA

81
Q

non-NMDA channels are permeable to what 2 ions

A

Na+ and K+

82
Q

NMDA channels are permeable to what 3 ions

A

Na+ Ca2+ and K+

83
Q

how many channels are non-NMDA channels permeable to

A

2

84
Q

how many channels are NMDA channels permeable to

A

3

85
Q

non-NMDA channels mediate ___ excitatory synaptic transmission in the CNS

A

fast

86
Q

NMDA channels contributes a ___ component to the excitatory synaptic potential

A

slow

87
Q

what promotes neurotoxicity with regard to NMDA receptors

A

high permeability to Ca2+

88
Q

give 2 drugs (anaesthetic agents) that are selective blockers of NMDA-operated channels

A

ketamine

psychomimetic agents - phencyclidine

89
Q

what is the role of metabotropic glutamate receptors

A

modulation of neurotransmission

90
Q

how do metabotropic glutamate receptors modulate neurotransmission

A

presynaptic inhibition - e.g. inhibition of Ca2+ channels

91
Q

what does NMDA stand for

A

N-methyl-D-aspartate

92
Q

what causes GBS

A

autoimmune damage to myelin sheath of PNS

93
Q

how does GBS present

A

changes to sensation/pain/muscle weakness - begins distally in hands and feet and spreads proximally to the arms and upper body

94
Q

where is ACh synthesised

A

axon

95
Q

where are neuropeptides synthesised

A

cell body

96
Q

give 5 symptoms of LMN disease

A 
hypo/areflexia
hypo/atonia
flaccid muscle weakness or paralysis
fasciculations
muscle atrophy

YEAR 3 NEURO (12 decks)

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