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BMS11004 > BMS11004 WEEK 10 - THURSDAY > Flashcards

BMS11004 WEEK 10 - THURSDAY Flashcards

sensory receptors, dorsal column, medial lemniscal projection, thalamus, cortex

1
Q

name 2 major input components in somatic sensory system

A

mechanical stimuli (light touch, vibration, pressure, cutaneous tension)
painful stimuli and temperature

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2
Q

what does the somatic sensory system allow us to do

A

identify shape, object textures
monitor internal/external forces
detect harmful situation
sense of self within environment and planning actions

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3
Q

name 3 sensory receptors with encapsulated nerve endings

A

Meissner (tactile) corpuscles
Pacinian (lamellated) corpuscles
Ruffini corpuscles

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4
Q

what are Meissner (tactile) corpuscles - encapsulated nerve endings of SNS
including location, modality, Hz, adaptations

A

in dermal papillae of skin, light touch modality (texture, movement), sensitive to 30-50H, rapidly adapting

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5
Q

what are Pacinian (lamellated) corpuscles - encapsulated nerve endings of SNS
including location, modality, Hz, adaptations

A

in dermis, joint capsules, viscera
deep pressure modality (stretch, tickle, vibration)
sensitive to 250-350Hz
rapidly adapting

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6
Q

what are Ruffini corpuscles - encapsulated nerve endings in SNS
including location, modality, Hz, adaptations

A

dermis, joint capsules, subcutaneous tissue
heavy touch, pressure, skin stretch, joint movements (proprioceptor
slowly adapting

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7
Q

name 2 unencapsulated nerve endings in SNS

A

Merkel (tactile) discs
Free-nerve endings

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8
Q

what are merkel (tactile) discs in unencapsulated nerve endings of SNS
including location, modality, Hz, adaptations

A

superficial skin (epidermis)
light touch, texture, edges, shapes
slowly adapting

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9
Q

what are free-nerve endings - uncapsulated nerve endings of SNS
including location, modality, Hz, adaptations

A

widespread in epithelia, connective tissue
heat and cold

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10
Q

what are cellular receptors made up of, with example

A

made up of multiple cells (merkel’s disc, free nerve endings, meissners corpuscle)

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11
Q

what are molecular receptors made up of with an example

A

made up of multiple components (stretch receptors)

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12
Q

name 2 types of mechanoreceptors (based on response)

A

rapidly adapting/phasic receptors
slowly adapting/tonic receptors

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13
Q

describe rapidly adapting (phasic) mechanoreceptors

A

when stimulated, neuron fires rapidly over time then stop= transient response, giving into about change to stimulus

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14
Q

give an example of a rapidly adapting (phasic) mechanoreceptor

A

pacinian corpuscle

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15
Q

describe slowly adapting (tonic) mechanoreceptors

A

continue to respond as long as stimuli present
giving into on persistence of stimulus

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16
Q

give example of slowly adapting (tonic) mechanoreceptor

A

ruffini corpuscle

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17
Q

how are primary afferent axons classified

A

by conduction velocity, reflecting diameter of axon
faster = wider diameter

18
Q

primary afferent axon subtypes - what are axons coming from skin classified as

A

designated by letters (A, B, C) from fastest to smallest
A group further broken down to alpha, beta

19
Q

primary afferent axon subtypes - what are axons coming from muscles classified as

A

designated by Roman numeral (I, II, III from largest - smallest)
I group broken into Ia…

20
Q

why are pain fibres slower than proprioceptors

A

need info from proprioceptors (regarding balance) quicker so we dont collapse but pain can be slower

21
Q

name 2 main routes (tracts) that somatosensory projection get to brain via

A

medial lemniscal tracts
spinothalamic tracts

22
Q

what does medial lemniscal tract carry to brain (somatosensory projection)

A

carry mechanoreceptive and proprioceptive signals to thalamus

23
Q

what does spinothalamic tract carry to brain (somatosensory projection)

A

carry pain and temperature signals to thalamus

24
Q

what 3 type of neurons does somatosensory projections (medial leminiscal and spinothalamic tracts) travel by

A

first/second/third order neurons

25
Q

what does first-order neurons in medial leminscal and spinothalamic tracts do

A

detect stimulus, transmits to spinal cord

26
Q

what does second-order neurons in medial leminscal and spinothalamic tracts do

A

relay signal to thalamus “gateway” to cortex

27
Q

what does third-order neurons in medial leminscal and spinothalamic tracts do

A

carry signal from thalamus, to cortex

28
Q

explain topological arrangement of axons (regarding 1st order) for upper body

A

1st order axon from upper body follows lateral pathway, synapses onto 2nd order in cuneate nucleus

29
Q

explain topological arrangement of axons (regarding 1st order) for lower body

A

1st order axons from lower body follow medial pathway, synapses onto gracile nucleus neurons

30
Q

together, what is topological organisation of 1st order axons from upper/lower body known as

A

dorsal column nuclei

31
Q

describe topological arrangement of 2nd order axons in medial-leminiscal system

A

crosses midline and ascend in medial lemniscus
reverses topology so lower body axons are more lateral on reaching thalamus

32
Q

describe topological arrangement of 3rd order axons in medial lemniscus system

A

reverse topology - lower body axon synapses onto medial cortical neurons, but upper body axons map to lateral cortex

33
Q

what does topological mean

A

mapping body and physiological distributions in cortex

34
Q

what are dermatomes

A

specific patch of skin innervated by sensory ganglion, with dermis from specific somite in embryo

35
Q

what does somatosensory homonculus mean?

A

map along the cerebral cortex of where each part of the body is processed, representations not proportional

36
Q

what does receptive fields mean, and how is it measured

A

size depends on where it is located, measured by assessing ability to discriminate 2 sharp points set apart at different distances

37
Q

when measuring receptive field, what does it mean when subject can feel 2 pin point

A

distance between points is larger than receptive field

38
Q

what does large receptive field mean (in terms of discrimination)

A

low discrimination= arms and legs

39
Q

what does small receptive field mean, in terms of discrimination

A

high discrimination
cortex more dedicated to regions for smaller receptive field

40
Q

whereabouts in brain is somatotopic map preserved

A

coronal plane, postcentral gyrus with different sensory modalities being localised along our sagittal axis

41
Q

what does loss of stimulation of specific body area lead to in the cortex

A

disappearance of area devoted to area and increase in neighbouring patch

BMS11004 (29 decks)

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