Lecture 6: sensory systems Flashcards

1
Q

Sensation can be categorized into what 2 main types

A

Conscious and nonconcious

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2
Q

What are the 2 main divisions of conscious sensation

A

Exteroreceptiom and proprioception

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3
Q

What are the 2 divisions of the non conscious sensation

A

Enteroreception and proprioception

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4
Q

True of false: proprioception can be conscious and non conscious

A

True

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5
Q

What is general external stimuli called

A

Exteroreceptiom

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6
Q

What is general internal stimuli called

A

Enteroreception

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7
Q

Explain exteroreception

A

External stimuli
Eg: sensations detected by cutaneous receptors

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8
Q

Explain enteroreception

A

Internal stimuli
Eg. visceral sensation related to homeostasis (bp, hr)

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9
Q

True or false: external stimuli is felt by enteroreceptors

A

False, by cutaneous receptors

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10
Q

What does kinesthesia mean

A

Body’s location and movement in space

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11
Q

Explain concious sensation

A

Pathways to cerebral cortex (typically via thalamus)
awareness and ability to move body parts without visual cues

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12
Q

Concious sensation have pathways to cerebral cortex or cerebellum

A

Cerebral cortex

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13
Q

Concious sensations have pathways to the cerebral cortex via what structure typically

A

Thalamus

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14
Q

Explain non conscious sensation

A

Pathways to the cerebellum
Coordination of complex movements (eg ealking, riding a bike)

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15
Q

Non conscious sensation has pathways to cerebral cortex or cerebellum

A

Cerebellum

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16
Q

Somatosensatio. Includes what types of modalities

A

Vibration
Light touch
Pain
Temp
Proprioception

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17
Q

What are some general categories of receptors in somatosensatio

A

Mechanoreceptors
Nociceptors
Thermoreceptors

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18
Q

What do mechanoreceptors detect in terms of internal stimuli

A

Proprioception, stretch in blood vessels

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19
Q

What do mechanoreceptors detect in terms of external stimuli

A

Light touch, vibration, stretch , pressuee

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20
Q

What do nociceptors detect

A

Damaged (or potentially damaged) tissue and associated chemical changes (ex, burns)

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21
Q

What do thermoreceptors detecr

A

Relative changes in temperature (within normal range)

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22
Q

In the change in temp is outside the normal range, which receptor detects it

A

Nociceptors

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23
Q

What are the 6 cutaneous receptors

A

Free nerve ending
Lamellar (pacinian) corpuscle
Type 1 cutaneous mechanoreceptor (merkel disk)
Tactile/touch receptor (Meissener corpuscle)
Type 2 cutaneous mechanoreceptos (ruffini corpuscle)
Hair follicle receptor

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24
Q

What 3 cutaneous receptors are un encapsulated

A

Free nerve endings
Type 1 cut mechanoreceptor (merkel)
Hair follicle receptor

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25
Q

What 3 cutaneous receptors are encapsulated

A

Lamellar (pacinian) corpuscle
Tactile/touch (meissner) corpuscle
type 2 cuteanous mechanoreceptors

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26
Q

Tru or false : if a receptor is encapsulated (connective tissues surrounding it) , it is not as sensitive to light sensations

A

True

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27
Q

Explain free nerve endings

A

Unencapsulated
Detect pain and temp

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28
Q

Which cut receptor is Unencapsulated and
Detect pain and temp

A

Free nerve ending

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29
Q

True or false, free nerve endings are located deep

A

False, they go into the epidermis and are close to surface

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30
Q

Explain lamellar (pacinian) corpuscle

A

Encapsulated
Detect high frequency vibration and sudden changes in pressure

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31
Q

Which receptor is Encapsulated and
Detect high frequency vibration and sudden changes in pressure

A

Lamellar corpuscle

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32
Q

Explain type 1 cutaneous mechanoreceptor (merkel)

A

Unencapsulated
Sense light touch and pressure

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33
Q

Which receptor is Unencapsulated and
Sense light touch and pressure

A

Type 1 cutaneous mechanoreceptor (merkel)

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34
Q

Explain tactile/touch corpuscle (meissner)

A

Encapsulated
Sense light and low frequency vibration

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35
Q

Which receptor is Encapsulated and
Sense light and low frequency vibration

A

Tactile/touch corpsucle (meissner)

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36
Q

Wxplain type 2 cutaneous mechanoreceptor (ruffini)

A

Encapsulated
Sense stretch and sustained pressure

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37
Q

Which receprr is. Encapsulated and
Sense stretch and sustained pressure

A

Type 2 cutaneous mechanoreceptor (ruffini)

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38
Q

Explain hair follicle receptor

A

Unencapsulated
Sense movement on skin surface that disturbs hair

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39
Q

Which receptor is Unencapsulated and
Sense movement on skin surface that disturbs hair

A

Hair follicle receptor

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40
Q

what are the two encapsulated proprioceptors

A

muscle spindles and golgi tendon organs

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41
Q

How many neuron pathways are in typical somatosensory pathways

A

Primary (1o; first order) neuron = cell bodies in dorsal root ganglia
• Secondary (2o; second order) neuron= axons decussate
• Tertiary (3o; third order) neuron=cell bodies in thalamic nuclei

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42
Q

Where are the cell bodies of primary neutrons located

A

Cell bodies in dorsal root ganglia

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43
Q

Where do the axons decussate

A

At secondary neuron

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44
Q

Where are the cell bodies of tertiary neutrons located

A

cell bodies in thalamic nuclei

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45
Q

true or false: tertiary neutron cell bodies are located in the dorsal root ganglia

A

false, in the thalamic nuclei

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46
Q

the somatosensory pathways are broadly divided into what 2 systems

A

1) dorsal Column system
2) anterolateral sustem and non conscious proprioception pathways

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47
Q

the dorsal column system is mainly responsible for what sensations

A

fine touch, vibration, and conscious proprioception

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48
Q

what is the pathways of the dorsal column system

A

dorsal column-medial leminscus

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49
Q

the anterolateral system and non conscious proprioception pathways are mainly responsible for what sensations

A

pain, temperature, crude touch, and non conscious proprioception

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50
Q

be able to recognize general areas where the different somatosensory

A
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51
Q

the dorsal and ventral spinocerebellar pathways are responsible for concious or unconscious sensation

A

unconscious

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52
Q

what are the spinocerebellar pathways

A

dorsal and ventral spinocerebellar pathways

53
Q

what are the spinothalamic pathways

A

lateral and anterior spinothalamic

54
Q

which pathways take the signal rom spine to cerebellum

A

dorsal and ventral spinocerebellar pathways

55
Q

which pathways take the signal from spine to thalamus

A

lateral and anterior spinothalamic

56
Q

primary neurone are what type of neurons

A

pseudo unipolar

57
Q

where is the location of the cell body is pseudounipolar

A

centrally

58
Q

primary neurone synapse with secondary neurone where (2 areas)

A

in the brain stem nucleus or dorsal horn (depending on the pathway)

59
Q

at the end of the primary neurone what receptors are tehre

A

cutaneous

60
Q

which are the neurons that cross the midline (decussate)

A

secondary neuron

61
Q

the synapse between secondary and tertiary neurons always happens where

A

thalamus

62
Q

secondary and tertiary neurons are what type

A

multipolar

63
Q

what is the general pathways for the dorsal column medial lemiscus

A

1) primary sensory neuron enters doorsla horn (cell. body in dorsal root ganglion)
2) ipsilateral dorsal (post column)
=t6 above: fasciculus cuneatus,
=below T6 :fasciculus gracilis
3) synapse with secondary neurone (either in nucleus cuneatus or gracilis)
4) decussation (internal arcuate fibers)
5) medial lemniscus
6) synapse with tertiary neurone (in VPL or VPM nucleus of thalamus)
7) internal capsule (posterior limb)
8) corona radiata
9) primary sensory gyrus (post central gyrus)

64
Q

in the DCML, primary sensory neurons (that come form periphery) axons enter where

A

enter the dorsal horn

65
Q

true or false: primary sensory neurons synapse in the dorsal horn

A

false, immediately enter the dorsal columnb

66
Q

in DCML, what happens to the primary seocnsry neurone immediately after enter the dorsal horn

A

immediately enters the dorsal poster horn

67
Q

in DCLM, what happens the the primary sensory neuron signal immediately after entering the dorsal COLUMB

A

ascends spinal cord in fascicles cuneatus or fasculis gracilis

68
Q

in the DCML, if the signal comes from spinal level T6 and above, where does it ascend the spinal cord

A

ascends in the fasciculus cuneatus

69
Q

in the DCML, if the signal comes from below T6, where does it ascend the spinal cord

A

ascends in the fasciculus gracilis

70
Q

in the DCLM, what is the division between the fasciculus cuneatus and gracilis called

A

dorsal (posterior) intermediate septum

71
Q

in DCML, fasciculis cuneatus is associated with what spinal levels

A

t6 and above

72
Q

in DCML< fasciculis gracilis is associated with what spinal levels

A

below t6

73
Q

explain the somatotropin organization of dorsal (posterior) column

A

primary sensory neurons from lumbosacral region = more medial

from cervical region= lateral

74
Q

in the dorsal (posterior) column, primary sensory neurons from the lumbosacral region are more lateral or medial

A

medial

75
Q

in the dorsal (posterior) column, primary sensory neurons from the cervical region are more lateral or medial

A

lateral

76
Q

explain why primary sensory neurons from lumbosacral are more lateral in the dorsal columb

A

axons are pushed more medially as more dorsal rootlets enter spinal cord at each level (from caudal to rostral)

77
Q

in DCLM, where do primary neurons synapse with secondary sensory neurons

A

in the nucleus cuneatus or nucleus gracilis, depending on origin of the sensory info

78
Q

in DCML, if the signal is from t6 and above, where do primary neurons synapse with secondary neurons

A

nucleus cuneatus

79
Q

in DCLM< if the signal is from below t6, where do primary neurons synapse with secondary neurons

A

nucleus gracilis

80
Q

in DCML, level of sensory decussation is where

A

near the centre of the medulla oblongata in the longitudinal direction (rostral to the decussation of the pyramids, (motor pathway) but caudal to the level of the open medulla

81
Q

in DCML, decussating secondary sensory neuron axons form what

A

the internal arcuate fibres

82
Q

where is the ML tract located in relation to the rostral medulla

A

medial lem dorsal to the pyramids, near the midline

83
Q

in DCML, secondary sensory neurons synapse with tertiary sensory neurons where (be specific)

A

in one of the ventral posterior nuclei of the thalamus (either lateral or medial)

84
Q

in DCML, for secondary sensory neurons coming from the body (including axial and appendicular tissues), where do they synapse

A

in the ventral posterior lateral nuclei of the thalamus

85
Q

in DCML, for secondary sensory neurons coming from the face (via trigeminal), where do they synapse

A

in the ventral posterior medial nuclei of the thalamus

86
Q

true or false,in DCML, for secondary sensory neurons coming from the body (including axial and appendicular tissues), they synapse inin the ventral posterior medial nuclei of the thalamus

A

false, in the ventral posterior lateral nuclei of the thalamus

87
Q

true or false: the thalamus is the relay centre

A

true

88
Q

what is the thalamus (in general)

A

large, paired nuclei in the diencephalon

89
Q

what part of the brain is the thalamus located

A

diencephalon

90
Q

true or false: all conscious and non conscious must be relayed thru the thalamus en route to the primary cortices except olfaction

A

false, only ALL CONCIOUS (except olfactory)
=no nonconcious

91
Q

all concious sensation is relayed thru the thalamus en route to the primary cortices except what sensation

A

olfaction

92
Q

true or false, only sensory Information goes thru thalamsu

A

false, also accessory motor pathways (ex: control and coordination)

93
Q

axons of the tertiary sensory neurons contribute to what

A

the internal capsule (white matter tract) =specifically the posterior limb and genu

94
Q

is the internal capsule white or grey matter

A

white matter trasht

95
Q

what is the location of the internal capsule

A

it is situated lateral to the thalamus and caudate nucleus, and medial to the lentiform nucleus.

96
Q

which two structures what the lentiform nucleus

A

globus pallidus (medial) and putamen (lateral)

97
Q

in DCLM, in the internal capsule, somatosensory info from the face contributes to what part of the internal capsule

A

contributes to the genu of the internal capsule (bend)

98
Q

in the internal capsule, somatosensory info from the cervical to lumbar contributes to what part of the internal capsule

A

it is arranged from rostral (cerical) to caudal (lumbar)

99
Q

in the DCML, do axons of tertiary sensory Hurons contribute more to the anterior or posterior limb of the internal capsule

A

posterior limb (and genu)

100
Q

where is the posterior limb of the internal capsule locaeted

A

between the thalamus and lentiform nucleus (GP and P)

101
Q

what is the lentiform nucleus

A

nuclei (collection of cell bodies) involved in motor control

102
Q

is the lentiform nucleus involved in sensory or motor control

A

motor control

103
Q

what is a nuclei

A

collection of cell bodies

104
Q

axons of the tertiary sensory neurons join the BLANK before terminating in the primary somatosensory cortex

A

corona radiata

105
Q

what is the corona radiate

A

sensory fibres somethimes reference to thalamocortical fibres)

106
Q

where do axons of the tertiary sensory neurons terminate

A

in the primary somatosensory cortex (according to somatotropin arrangement)

107
Q

going medial to lateral, what is the somatotropin organization of the lower limb, upper limb, trunk and face

A

medial to lateral =
lower limb (in the longutinatl median fissure), trunk, upper limb, face

108
Q

be able to draw out the pathways for the DCML

A
109
Q

what do lesions of the DCML pathway lead to deficits in

A

fine (discriminative) touch , vibration, and conscious proprioception

110
Q

what is tabes dorsals (aka progressive locomotor ataxia)

A

a progressive degenerative disorder of the dorsal columns and dorsaal roots of the spinal cord

111
Q

in tabes dorsalis, what is demyelination caused by

A

untreated neurosyphilis infection

112
Q

which of these sensations are not carried by the DCML pathway

a) nociception
b) conscious proprioception
c) vibration
d) non conscious proprioception

A

a: nociception
d) non conscious proprioception

113
Q

true or false: only golgi tendon organs and msucel spindles allow us to know our limb position in spavce

A

false
joint kinesthetic receptors in capsule of synovial joints are also believed to play a role in awreness of limb position and movement

114
Q

what are msucles spindles made of

A

intrafusal muscle fibers

115
Q

what do msucle spindles respond to

A

changes in msucle length

116
Q

where are golgi tensons located

A

near myotendinous junctions

117
Q

what is the function of golgi tendon organs

A

slow adapting response to tenssion (stretching) in tenson

118
Q

what are the neurons that cause main movement of limb in proprioeception

A

alphamotor neuron

119
Q

what neurons innervate the extrafusal fibers

A

alpha motor neurons

120
Q

what neurons innervate the intrafusal msucle fibers

A

gamma motor neurons

121
Q

what is function of gamma motor neurons

A

=innervate intrafusal fibers of msucle spindles to keep stretch receptors taut (ex; during concentric contraction)

=allow then the short in relation to extrafusal fibers (always taut)

122
Q

explain the organization of the ML tract in the rostral (open) medulla

A

lumbar= ventral

cervical= dorsal

123
Q

what is the location of the ML tract in the pons

A

licated in the dorsal aspect of the basilar (ventral pons)

124
Q

what is the somato organization of the ML in the poons

A

lumboscarcal = lateral
cervical =medial

125
Q

what is the location of the ML tract in the midbrain

A

ML is located medial to substantia nigra and dorsolateral to red nucleus

126
Q

what is the somato organization of the ML tract in the midbrain oppsoite to

A

rostral medulla

127
Q

what is the somato organization of the midbrain for the ML travt

A

cervical = ventral
lumbar=dorsal

128
Q

after decussating, the tracts formed by 2 sensory neuron axons in the DCML are collectively called what

A

medial leminscus, until it converges on the nucleus of thalamus

129
Q

what is the division between fasciculus gracilis and cuneatus called

A

dorsal (posterior) intermediate septum