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Neuroscience and mental health > PNS > Flashcards

PNS Flashcards

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1
Q

what does the PNS include

A

everything except for the brain and spinal cord ie spinal and cranial nerves

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2
Q

what is the role of the PNS

A

it is the communication centre between the CNS and the body

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3
Q

2 main branches of the PNS

A

sensory and motor

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4
Q

2 branches of motor

A

autonomic and somatic

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5
Q

what does the somatic nervous system do

A

controls voluntary movement

skeletal muscle

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6
Q

what does the autonomic nervous system do

A

control involuntary responses

eg Bp and heart rate

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7
Q

branches to the autonomic nervous system

A

sympathetic and parasympathetic

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8
Q

describe the sympathetic nervous system

A

mobilises body systems

flight/fight responses

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9
Q

describe the parasympathetic action

A

conserves energy

rest and digest responses

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10
Q

what do sensory neurons do

A

carry information from sensory receptors in the skin and the viscera to the brain

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11
Q

which section is the cranial section

A

the head portion

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12
Q

what does the non-neuronal ectoderm give rise to in the development of neural crest cells

A

the skin

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13
Q

what does the neuronal ectoderm give rise to in the development of neural crest cells

A

cns

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14
Q

what does the neuronal fold give rise to in the development of neural crest cells

A

neuronal crest cells
they migrate - many lineages
between the skin and cns - relay information between them

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15
Q

what forms from neuronal crest cells

A

sensory neurons

and shwann cells

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16
Q

describe the structure of the sensory neuron

A

pseudounipolar
peripheral process - signal from skin/viscera to soma
central process to spinal cord

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17
Q

summarsie the structures of fibres A to C

A

a - myelinated somatic
b - myelinated visceral
c - unmyelinated somatic and visceral pain afferents

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18
Q

describe the structure of a fibres

A

free nerve endings
pseudounipolar
for pain

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19
Q

describe the structure of b fibres

A

encapsulated nerve endings
connective tissue capsule
pseudounipolar
pressure Pacinian corpuscle

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20
Q

describe the structure of c fibres

A

dipolar?

hearing hair cells in ear

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21
Q

describe the structure of d fibres

A

smell

cell body not in the ganglion

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22
Q

what does the motor division do

A

efferent

composed of motor neurons carry signal from CNS to effectors

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23
Q

describe the SNS

A

made of efferent nerves, important for muscle contraction
nerve signals begin in motor cortex
can be voluntary or automatic
nerves terminate at the NMJ to give a response
upper motor neurons in primary cortex are part of the CNS
lower motor neurons part of the PNS, cause response eg in reflex
neurons synapse with the brain stem and the spinal cord. lower motor neuron continue to skeletal muscle

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24
Q

development of the motor neurons

A

in lower part of the basal plate the lower motor neurons generate from the spinal cord itself

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25
what is a motor unit
1 motor neuron innovates a range of muscle fibres
26
describe the peripheral processes of the sensory neurons
dorsal root | cell bodies in the dorsal root ganglion
27
describe the peripheral processes of the motor neurons
leave the spinal cord via the ventral root
28
where do the motor and sensory nerves go after their respective roots
mixed in the spinal nerve the spinal nerve leaves through the invertebral foreman spinal cord divide into posterior rami - ignal to skin on back, and ventral rami - feed front of body paravertebral sympathetic chain ganglion goes into 2 rami
29
how many nerves are in the PNS
43 pairs
30
groups of spinal nerves
``` cervical plexus brachial plexus cervical enlargement intercostal nerves lumbar enlargement lumbar plexus sacral plexus cauda equina ```
31
describe the autonomic nervous system
efferent nerves and ganglia stimulating effectors out of our control made of sympathetic and parasympathetic composed of 3 neurons
32
describe the 3 neurons that make up the ANS
from hypothalamic nucleus (visceral motor nuclei) to brain stem nuclei/spinal cord preganglionic neuron from spinal cord/brain stem to autonomic ganglia (pre synaptic if from vagal nerve/sacral parasympathetic nerves) postganglionic from autonomic ganglia to visceral effectors (post synaptic if from vagal nerve/sacral parasympathetic nerves)
33
which nerves in the ANS are myelinated
preganglionic
34
describe the divisions of the ANS
nerves from T1 - L2 go to sympathetic chain | from here nerves go to the collateral ganglion or straight to organs
35
where do preganglionic or presynaptic neurons arise from
basal plate in spinal cord
36
difference between dorsal root ganglia and autonomic ganglion
dorsal exclusively contains cell bodies | autonomic ganglia has cell bodies and dendrites associated with synapses
37
how is the myelin sheath formed
from shwann cells that wrap around axon clockwise
38
features of the myelin sheath
major dense line (period line) - where the cytoplasm is condensed minor dense line (intraperiod line) - plasma membrane node of Ranvier allows saltatory conduction to take place
39
describe the myelination of C fibres
wrapped by 1 layer of the shwann cell and cytoplasm - neurilemma many fibres are wrapped by the membrane of 1 neuron
40
describe A fibres
largest fibres 5-20microns - less resistance myelinated somatic - sensory and motor to skeletal muscle fast transmission 130m/s
41
what is the propagation speed of a nerve impulse controlled by
size - larger = less resistance = faster myelination - myelinated = saltatory conduction = faster temperature
42
describe B fibres
medium size - 2-3microns 15m/s myelinated visceral - sensory and autonomic preganglionic
43
describe C fibres
``` smallest 0.5 - 1.5microns 2m/s unmyelinated sensory and autonomic motor pain ```
44
explain how rootlets, roots, rami and ganglia link
rootlets form dorsal and ventral roots which go into rami
45
how many cranial ganglia are there
4
46
name the 4 cranial ganglia
ciliary ganglion otic ganglion pterygopalatine ganglion submandibular ganglion
47
describe the 3 sympathetic paravertebral and collateral pathways
preganglionic neuron goes through the ventral ramus then either: - through white ramus, synapse, postganglionic exits through the grey ramus to the spinal cord - preganglionic move up/down the sympathetic trunk and synapse in the sympathetic ganglion - pass through white ramus to splanchnic nerve and synapse later in the collateral ganglion
48
where does the collateral ganglion lead to
the liver, spleen, adrenal glands, stomach, intestines, kidneys, urinary bladder, reproductive organs
49
where do the nerves from the grey ramus go
sweat glands, piloerector muscles, bv of skin and skeletal muscles
50
where do nerves from the sympathetic ganglion go
``` iris salivary glands lungs heart thoracic oesophagus ```
51
what are nerve plexuses
networks of successive ventral rami that exchange fibres (crisscross and redistribute) mainly innervate the limbs lumbosacral and brachial plexus innervate the skin thoracic ventral rami don't form nerve plexuses
52
what innovates dermatomes
dorsal root of the spinal nerves
53
describe dermatomes
skin is continuous - can have overlap area of skin supplied by single spinal nerve root stacked along the thorax and abdomen longitudinally along the limbs
54
clinical significance of dermatomes
can use pin prick test to determine the site of spinal damage
55
describe visceral afferents
not part of autonomic ns nerve fibres from the organ - use sympathetic nervous system pass through splanchnic nerves and plexuses, sympathetic collateral, and paravertebral ganglia and white rami to get to spinal dorsal root
56
describe the cutaneous distribution of peripheral nerves
area of skin supplied by a nerve that comes off a plexus (eg brachial and lumbosacral plexus to upper and lower limbs) sensory neurons of the peripheral nerve may come from >1 spinal root eg lateral antebrachial cutaneous - C5-7
57
clinical significance of cutaneous distribution of peripheral nerves
identify which individual peripheral nerve is damaged by pin prick exam
58
describe myotomes
muscles that are supplied by single motor neuron root ventral root some muscles are supplied by >1 root all muscle is supplied by the root of that nerve
59
describe peripheral neuropathies
damage/disease affecting PNS nerves may impair sensation, movement gland or organ function sensory nerves - tingling, pain and numbness motor nerves - weakness to hands and feet autonomic nerves - changes in heart rate or bp
60
describe monopathy
single nerve being affected | diabetic - ocular motor nerve - eye
61
describe polyneuropathy
several nerves are affected | gillian barre - inflammatory
62
causes of peripheral neuropathies
metabolic, toxic, inflammatory, traumatic, genetic, idiopathic
63
structure of nerve
Connective tissues: endoneurium - around each individual neuron, loose collagen fibrils perineurium - around a fascicle (bundles of neurons and axons) - give tensile strength made of collagen [between fascicles - have bv] epineurium - around the entire nerve, dense, collagenous, have a blood supply, some fatty tissue
64
where is the PNS nerve structure present
on everything beyond the spinal cord
65
describe neuropraxia
``` small compression axon can be repaired reversible conduction block selective demyelination of axon sheath endoneurium and axon still in tact ```
66
describe axonotmesis
demyelination and axon loss epineurium and perineurium remain in tact still some continuity with the nerve degeneration below and proximal to the site of injury
67
describe neurotmesis
more sever injury - less likely for complete recovery scaffold disrupted associated with complete nerve division and disruption seen after toxic/ischemic injuries damage to endoneurium, perineurium and epineurium, around centre of nerve - no nerve growth (different degrees eg endo, endo and peri, endo and peri and epi)
68
describe axon regeneration
distal portion of axon is phagocytosed - remove myelin and axon - Wallerian degeneration proximal end of nerve fibre regenerating into tube of shwann cells - stump from axon grow, try to reach tissues shwann cell proliferate
69
what happens in a neuroma
axon doesn't find final position | makes nerves there
70
what does avulsed mean
not in tact
71
what happens if there is avulsion in the ventral root and dorsal root
ventral: degeneration - it is not attached to the cell body | in dorsal cell body is attached so still intact
72
how do you do an EMG
put needle in muscle
73
what is the purpose of an EMG
distinguishes between myopathies and muscle weakness due to nerve pathology
74
what creates a larger response on the EMG
the fibre being closer to the electrode
75
ehat is myopathy
damage to the muscle fibre
76
what is the effect of myopathy on contractions
they are spontaneous less frequent than in the nerves signal is smaller
77
what is a nerve conduction study
a diagnostic technique for evaluating the speed of nerve impulses
78
Describe the NCS
``` involves the median nerve (in arm) electrodes are placed on the nerve create an electric field this stimulates the nerve the EMG is recorded at the surface ```
79
calculation for the conduction velocity
distance cm/(proximal latency - distal latency ms)
80
difference in latency between proximal and distal electrodes
proximal has a larger latency time
81
what can you measure in a NCS
NCV in m/s | amplitude of responses in mV
82
conditions you can see with a NCS
anoxopathies (from amplitude) and demyelinating neuropathies (from NCV)
83
what are axonal neuropathies
damage to the axons
84
result of axonal neuropathy
reduced amplitude
85
result of demyelination in NCS
proximal is delayed
86
result of demyelination and a conduction blocker in NCS
lower amplification more delayed Gillian Barre syndrome
87
what is a somatosensory evoked potential
evaluation of the site of a lesion in somatosensory pathways by assessment of amplitude and latency
88
why do you need to average many responses
the amplitude from the nerve responses is very small | so need averaging of 100 samples to get rid of noise
89
where do you put the electrodes in SEP
``` lower neck back of the neck cortex thalamus spinal area ```
90
how can you tell there is a lesion in SEP
there is a delay
91
alternative method to SEP to confirm a lesion
take a biopsy
92
which nerves don't have ganglia
sacral and vagus
93
what type of nerve fibres are preganglionic and presynaptic
myelinated b fibres | multipolar
94
where do the postganglionic and synaptic fibres arise from
the crest cells
95
describe the postganglionic and synaptic fibres
multipolar | unmyelinated c fibres
96
what is the effect of a denervated muscle on an EMG
damaged nerve surrounding nerves take over larger signal there fibrillation

Neuroscience and mental health (14 decks)

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