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

PHYSIOLOGY - Neurones, nerve conduction and synaptic transmission Flashcards

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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
is Na/K/ATPase involved in repolarisation
no
26
what often occurs with repolarisation
undershoot of RMP making membrane potential more negative
27
what is meant by the absolute refractory period
once the sodium channels close after an AP they enter an inactive state when they can't be reopened regardless of the membrane potential
28
what is meant by the relative refractory period
the Na ions slowly come out of inactivation during which time they may be excited with stimuli stronger than one normally needed
29
the refractory period ensures ....
unidirectional flow of AP
30
what is the overshoot
brief period when polarity is reversed to inside positive
31
what is the resting membrane potential of a neurone
- 70
32
why do passive signals not spread far from their site of origin
current loss across the membrane accompanied by a reduced change in potential - leaky membrane
33
what is ohm's law
V= IR
34
for a given current, the potential change increases/decreases linearly with membrane resistance
increases
35
what is the equation for length constant (lambda)
( rm / ri )^0.5
36
the ____ the length constant, the further the local current spread and so the higher the AP conduction velocity
longer
37
the _____ the length constant, the higher the AP conduction velocity
longer
38
give 2 ways in which the passive current spread could be increased
decrease axial resistance | increase membrane resistance
39
how could axial resistance be reduced
increase diameter of axon
40
how could membrane resistance be increased
insulation - myelin sheath
41
what cells provide myelin in the CNS
oligodendrocytes
42
what cells provide myelin in the PNS
Schwann cells
43
schwann cells and oligodendrocytes are both types of ____ cells
macroglial cells
44
true/false | a single schwann cell can insulate up to 50 axons
false | an oligodendrocyte can, but a schwann cell can only insulate 1 axon
45
myelin increases/decreases membrane capacitance
decreases
46
what is saltatory conduction
AP jumps from one node of ranvier to the next
47
what clusters are the nodes of ranvier
voltage activated Na+ channels
48
give 2 disorders that would cause slowing or cessation of nerve conduction
MS (CNS) | Guillian Barre Syndrome (PNS)
49
what are the 8 steps in chemical neurotransmission at the synapse
``` 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
what holds the pre and post synaptic membranes together
matrix of fibrous extracellular protein within cleft
51
where are the active zones and what are they
pre-synaptic membranes | vesicles cluster around them and opposite to neurotransmitter receptors
52
what are the 3 types of synapse and what is the most common
axodendritic - most common axosomatic axoaxonic
53
what is the main excitatory transmitter in the CNS
glutamate
54
glutamate activates the post-synaptic, ____ selective (__), ___tropic glutamate receptors generating a local, graded, excitatory response
``` cation selective (Na+) ionotropic ```
55
excitatory stimulation causes ____
depolarisation
56
glutamate generates a _._._._
EPSP | excitatory post synaptic potential
57
what are the main inhibitory transmitters in the CNS
GABA or glycine
58
what is the actual name of GABA
gamma - aminobutyric acid
59
GABA/glycine activate a postsynaptic, ____ selective (__), ___tropic GABAa/glycine receptors generating a local, graded inhibitory response
``` anion selective (Cl-) ionotropic ```
60
inhibitory stimulation causes ____
hyperpolarisation
61
GABA/Glycine generate a _._._._
IPSP | inhibitory post synaptic potential
62
what are the 3 main amino acid neurotransmitters in the CNS
glutamate glycine GABA
63
what is spatial summation
how many of each type of stimulation (inhibitory/excitatory) a neuron is receiving - many inputs converge upon a neurone to determine its output
64
what is temporal summation
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
name 4 amine neurotransmitters
dopamine histamine noradrenaline (NA) serotonin (5-HT)
66
Ach, amino acids and amines are released from ___
synaptic vesicles
67
peptides are released from ____
secretory vesicles
68
what neurotransmitters can activate ionotropic ligand gated channels
``` glutamate gaba glycine Ach 5-HT ```
69
all except ___ can activate metabotropic G protein coupled receptors
glycine
70
ionotropic/metabotropic receptors mediate slow neurotransmission
metabotropic
71
ionotropic receptors mediate ___ neurotransmission
fast
72
what receptors use direct gating
ionotropic ligand gated ion channels
73
how do metabotropic receptors use indirect gating
neurotransmitter acts on a G-protein complex that is distinct from the ion channel it controls
74
how do ionotropic receptors use direct gating
receptor is an integral part of the channel it controls
75
cholinergic synaptic transmission in autonomic ganglia uses both direct and indirect transmitter action. Fast EPSP is due to ionotropic ____ Ach receptors - channels conduct __ and __
nicotinic | Na+ and K+
76
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
muscarinic | K+ (m-type)
77
true/false | glutamate has inhibitory function aswell
true - via metabotropic glutamate receptors
78
how can ionotropic glutamate receptors be classified
response to non-endogenous agonists that mimic glutamate
79
which receptors bind the agonist that mimics glutamate
non-NMDA receptors
80
give 2 examples of exogenous agonists that mimic glutamate and bind to non-NMDA receptors
kainite or AMPA
81
non-NMDA channels are permeable to what 2 ions
Na+ and K+
82
NMDA channels are permeable to what 3 ions
Na+ Ca2+ and K+
83
how many channels are non-NMDA channels permeable to
2
84
how many channels are NMDA channels permeable to
3
85
non-NMDA channels mediate ___ excitatory synaptic transmission in the CNS
fast
86
NMDA channels contributes a ___ component to the excitatory synaptic potential
slow
87
what promotes neurotoxicity with regard to NMDA receptors
high permeability to Ca2+
88
give 2 drugs (anaesthetic agents) that are selective blockers of NMDA-operated channels
ketamine | psychomimetic agents - phencyclidine
89
what is the role of metabotropic glutamate receptors
modulation of neurotransmission
90
how do metabotropic glutamate receptors modulate neurotransmission
presynaptic inhibition - e.g. inhibition of Ca2+ channels
91
what does NMDA stand for
N-methyl-D-aspartate
92
what causes GBS
autoimmune damage to myelin sheath of PNS
93
how does GBS present
changes to sensation/pain/muscle weakness - begins distally in hands and feet and spreads proximally to the arms and upper body
94
where is ACh synthesised
axon
95
where are neuropeptides synthesised
cell body
96
give 5 symptoms of LMN disease
``` hypo/areflexia hypo/atonia flaccid muscle weakness or paralysis fasciculations muscle atrophy ```

YEAR 3 NEURO (12 decks)

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