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Neurophysiology Flashcards

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1
Q

What does the CNS contain

A

brain and spinal cord

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2
Q

what the PNS

A

mainly nerves which are enclosed bundles of the long fibres or axons, connext the CNS to every other part of the body

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3
Q

what does the PNS include

A

motor neurons, the autonomic nervous system and the parasympathetic nervous system

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4
Q

what is the Autonomic nervous system

A

regulates involuntary functions

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5
Q

what is the parasymapthetic nervous system

A

housekeeping, conserves energy

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6
Q

whats the enteric nervous system

A

regulates the GIT system

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7
Q

whats the sympathetic nervous system

A

mobilises body during fight or flight

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8
Q

Whats a neurons most fundamental property

A

Communicates with other cells via synapses

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9
Q

What are glial cells

A

non-neuronal cells that supply support and nutrition, form myelin

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10
Q

What are a typical neurons 3 parts

A

soma/cell body, dendrites and axon

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11
Q

4 main functions of glial cells

A

surround the neuron, supply nutrients and O2, insulate one from another, destroy pathogens and remove dead neurons

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12
Q

What is the membrane potential

A

the potential difference across a living cell membrane

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13
Q

If more positive ions are pumped out than in, it is called

A

an electrogenic pump

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14
Q

The task of the pump is not to maintain the potential difference, but

A

maintaining concentration difference

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15
Q

What can the presence of all ions together determined the final value of the membrane potential be calculated by

A

The goldman Hodkin Katz eqn

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16
Q

A transient change of the membrane potential may occur in two ways according to the GHK equation:

A

1) Change in the concentrations 2) Change in the permeabilities.

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17
Q

How can the membrane potential be changed artificially

A

Depol or Hyperpol

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18
Q

What does Hyperpolarisation do

A

Gives negative potential to intracellular space to increase the polarization.

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19
Q

What does depol do

A

Depolarization: giving positive charge to intracellular space to reduce the membrane potential.

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20
Q

Generation of action potential depends on voltage-dependent ion channels. These channels may be blocked by:

A

TTX(tetrodotoxin): From marine fish venom. It specifically blocks voltage-dependent Na+ channels. • TEA (tetraethylammonium): Specifically blocks voltage-dependent K+ channels.

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21
Q

What is adaptation.

A

In a membrane gradually depolarized by slowly increasing potentials, opening of Na+ channels is followed by inactivation, and thus the Na+ influx is inhibited even at higher potential

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22
Q

What is summation

A

When sub-threshold stimuli is applied and frequently repeated, action potential may be triggered by a potential weaker than threshold.

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23
Q

Relative refractory period.

A

Strong stimuli applied between threshold and resting membrane potential may elicit new action potential

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24
Q

Absolute refractory period

A

Additional stimuli given during development of an action potential elicits no further action potential if given before downstroke reaches threshold again

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25
RHEOBASE.?
Minimal stimulus strength that can generate a response when applied for a long time
26
CHRONAXIA?
The minimal time necessary to elicit response if the stimulus strength is twice the rheobase
27
salutatory conduction?
myelinated fibres- action potential propagated by leaping from one node to another
28
what does impulse generation depend on?
Both on the strength and duration of the stimulus
29
Which is more apt for comparison -rheobase or chronaxie?
chronaxie - contains info on both strenth and duration
30
what is a nerve
an enclosed bundle of axons in the PNS
31
in the CNS what are analogous structures known as
tracts
32
endoneurium
CT encloses each axon in a nerve
33
perineurium
CT wraps each fascicle (bundle of axons)
34
epineurium
CT wraps entire nerve
35
how are nerves characterised
based on direction they travel
36
afferent nerves
conduct signals from sensory neurons TO the CNS
37
example of afferent nerve
mechanoreceptors in skin
38
efferent nerves
conduct signals FROM CNS along motor neurons to target muscles and glands
39
mixed nerves
both afferent and efferent - conduct incoming and outgoing info in same bundle
40
example of mixed nerve
n vagus
41
neurons can be
unipolar, bipolar, multipolar or pseudounipolar
42
what is the convergence phenomenon
The function of one neuron may be influenced by the function of more, on this neuron synapsing neurons together
43
what is divergence
The axon of one neuron may run to many other neurons through branches of the axon
44
If more than two neurons participate in the reflex
the pathway is polysynaptic
45
2 main effects neural networks can run through
EPSP, excitatory postsynaptic potential, depolarization (excitation) or IPSP, inhibitory postsynaptic potential, hyperpolarization (inhibition)
46
disfacilitation
inhibition of excitatory neuron
47
disinhibition
inhibition of inhibitory neuron
48
reverberation
Interneurons may inhibit or excite, collaterals between parallel neural pathways may generate returning signals
49
Evidences for intersegmental integration
1. Segments of the hindlimbs send inhibitory impulses to the forelimbs (Schiff-Sherrington phenomenon), 2. Scratch reflex
50
intersegmental level functioning of spinal cord?
processes occuring withou the control of the CNS
51
Spinal cord regions
cervical, thoracal, lumbal and sacral
52
what is grey matter
nerve cells
53
what is white matter
nerve fibres
54
where are Rexed's zones
grey matter
55
thickest parts of the spinal cord
cervical intumescentia
56
part of spinal cord that plays a role in moving FL
cervical intumescentia
57
part of spinal cord that plays a role in moving HL
lumbal intumescentia
58
cells that leave the vertebral canal
radicular cells
59
radicular cells include
Somatosensory cells somatomotor cells sympathetic cells parasympathetic cells
60
cells of the grey matter
excitatory and inhibitory neurons, | renshaw cells - establish connection between the given segments
61
do cells of the grey matter leave the spinal cord
no
62
what is a dermatome
skin area where sensory nerves relay info back to CNS
63
why are dermatomes imporant
for determination of the origin of skin sensitivity disturbances and in surgical anesthesia
64
what are head zones
Skin zones belonging to a visceral organ
65
why are head zones important
referred pain
66
what is a reflex
involuntary and nearly instantaneous movement in response to a stimulus.
67
5 main components of a reflex
receptor cell, afferent neuron, central processing unit, efferent neuron and effector cell
68
what is activated first in a reflex rxn - sensory or motor neuron
sensory
69
another name for spinal reflexes of spinal cord
somatosensory
70
the 2 most important somatic reflex arcs of the spinal cord
proprioceptive reflexes and exteroceptive reflexes
71
What is the proprioceptive reflex
receptor found in same organ as effector
72
What is the exteroceptive reflex
receptor found in different organ as effector
73
3 main types of proprioceptive reflex
1. myostatic 2. inverse myostatic 3. extensor thrust
74
how does the proprioceptive differ from the exteroceptive reflex
``` adequate stimulation is muscle stretching no latency its monosynaptic response immediate reflex doesnt fatigue ```
75
common features of proprioceptive and exteroceptive reflexes
local character response proportional to stim reciprocal innervation is typica higher brain levels modualte the reflex
76
the response to stretching is
contraction
77
What do Renshaw cells do
cause retrograde inhibition on both the motoneurons that are activating them and on the earlier mentioned interneurons that inhibit the flexors
78
What activates renshaw cells
the collaterals of excited alpha motoneurons
79
inverse stretch or myotatic reflex.
at further stretching a sudden relaxation occur
80
whats the extensor thrust
pressing sole of foot of animal against floor - stretch of interosseus muscle
81
exteroceptive reflex
from skin - outsde effector orgen
82
how are exteroceptive reflex different from proprioceptive
``` polysynaptic very long latency slow and long response reflex fatigues easy contralateral response evoked ```
83
exteroceptive reflex involves
nociceptive and thermoreceptors of skin, group 3 and 4 afferent fibres arrive to grey matter via spinal ganglia
84
what muscles are relaxed during exteroceptive reflex
ipsilateral extensor muscles
85
What muscles are extended in the exteroceptive reflex
activates ipsilateral flexor muscles
86
what are the clinical aspects of reflexes
mainly lesions - side of lesion can be localised they occur segmentally - location inside spinal cord specified reflexes are under upper CNS control - lesions here cause change in pattern of reflex
87
what is the Babinski sign
The forelimb is withdrawn by the animal (flexion), but on the digits instead of plantar flexion DORSIFLEXION is see
88
what does the babinski sign indicate
lesion in the corticospinal tract
89
walking and scratch pattern
more complicated but still carried out by control of spinal cord independent from the upper cerebral functions
90
characteristics of walking and scratch pattern (complex reflex of spinal cord)
stereotype extend to more segments rhythmically repeated last longer than the stimulus
91
what is needed to generate membrane potential
leaking k+ and na+ channel | ATPase pump
92
what does goldman-hodkin- katz equation show
the direction of ion flow
93
what influences the membrane potential significantly
permeability
94
when does a local response occur
occurs when depolarisation does not reach the threshold potential
95
what causes action potential
when depolarisation reaches the threshold potential
96
what specifically blocks the voltage dependent Na+ channels
TTX - tetrodotoxin
97
what specifically block the voltage dependent K+ channels
TEA - tetraethylammonium
98
in myelinated fibers propagation of action potential is
fast
99
in non myelinated fibers propagation of action potential is
slow
100
what is anterograde transport
from soma (body of the nerve cell) to nerve ending
101
what is retrograde transport
from nerve ending to soma
102
name the anterograde transport protein
kinesin
103
name the retrograde transport protein
dynein
104
what is a synapse
contact between an axon of one neuron and a dendrite or soma of another
105
which is a faster conductor of nerve impulses, chemical or electrical synapses
electrical
106
which synapse has bidirectional movement
electrical synapses
107
what is a gap junction
a special synapse that allows free diffusion of charges between cells
108
what structure of the gap junction allows this free diffusion of charge
connexon
109
what is a connexon
a hexamer built up of 6 connecting peptides
110
what is rectification
when one of the directions is more dominant
111
what cells are gap junctions associated with
cardiac cells
112
synaptic processes lead to(2)
EPSP - excitatory postsynaptic potential IPSP - inhibitory postsynaptic potential
113
which synapse has unidirectional movement
chemical synapses
114
what is the metabotropic effect
you can activate a cell in a way that alters their resting membrane potential for a long period of time

Physiology (2 decks)

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