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Neuroscience & Mental Health Y2 > Sensory Pathways > Flashcards

Sensory Pathways Flashcards

1
Q

WHAT ARE SENSORY MODALITIES?

A

 A MODALITY IS A TYPE OF STIMULUS

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2
Q

Speed of transduction, size of fibre, and state of myelination of fibre, and modality conducted of Abeta fibres?

A

Very fast transduction fibres- large and myelinated transmit mechanical stimulation e.g. brush

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3
Q

Speed of transduction, size of fibre, and state of myelination of fibre, and modality conducted of Adelta fibres?

A

Fast transduction (less fast and smaller than Abeta)- myelinated transmit pain/temperature

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4
Q

Speed of transduction, size of fibre, and state of myelination of fibre, and modality conducted of C fibres?

A

C Slow transduction, small and no myelination transmit slower achey pain, temperature, itch

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5
Q

Nerve endings of thermoreceptors?

A

Free nerve ending

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6
Q

Nerve endings of nociceptors?

A

Free nerve ending

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7
Q

Nerve endings of mechanoreceptors?

A

Nerve endings enclosed in connective tissue capsules

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8
Q

Nerve endings of auditory hair cells?

A

Special hair receptor cells

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9
Q

Nerve endings enclosed in connective tissue capsules are which type of receptor?

A

Mechanoreceptors

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10
Q

Free nerve endings are which type of receptor?

A

Nociceptors and thermoreceptors

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11
Q
  • Somatosensory receptors are X that convert energy from the environment into neuronal action potentials
A

transducers

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12
Q
  • The ABSOLUTE THRESHOLD of somatosensory receptors is the …
A

Level of stimulus (strength) that produces a positive response of detection 50% of the time

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13
Q

Thermoreceptors have what kinda nerve ending

A

Free nerve endings with high thermal sensitivity

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14
Q

Thermoreceptors have what kinda channels (2)

A 
-	4 heat-activated TRP channels:
TRPV1-4
-	2 cold-activated TRP channels:
TRPM8
TRPA1
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15
Q

What are the heat activated TRP channels

A

TRPV1-4

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16
Q

What are the cold activated TRP channels

A

TRPM8

TRPA1

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17
Q

What are the 4 mechanoreceptors

A

Meissners corpuscle, Merkel cells, Pacinian corpuscle and Ruffini endings

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18
Q

What type of touch stimulates Meissners corpuscle

A

Fine, discriminative touch

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19
Q

What type of touch stimulates Merkel cells

A

Light touch and superficial pressure

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20
Q

What type of touch stimulates Pacinian corpuscles

A

Detects deep pressure, vibration and tickling

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21
Q

What type of touch stimulates Ruffini endings

A

Continuous pressure or touch and stretch

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22
Q

Fine, discriminative touch stimulates what receptor

A

Meissners corpuscle

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23
Q

Light touch and superficial pressure stimulates what receptor

A

Merkel cells

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24
Q

deep pressure, vibration and tickling stimulates what receptor

A

Pacinian corpuscles

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25
Q

Continuous pressure or touch and stretch stimulates what receptor

A

Ruffini endings

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26
Q

How can mechanoreceptors be specific to types of touch

A

Through adaptation speed (fast and quick) and type of stimulus (continuous vs change)

27
Q

How do tonic receptors work in adaptation

A
  • Tonic receptors detect continuous stimulus strength
  • These do not adapt or adapt very slowly
  • Continue to transmit impulses to the brain as long as the stimulus is present
  • Keeps the brain constantly informed of the status of the body
  • E.G. MERKEL CELLS- slowly adapt allowing for fine touch perception
28
Q

How do phasic receptors work in adaptation

A
  • Detect a change in stimulus strength
  • Adapt quickly
  • Train of action potentials transmitted at start (when pressure excited the receptor), and then at end (when pressure is released)
  • Also called “movement receptors” or “rate receptors”
  • E.G. PACINIAN RECEPTOR
29
Q

What is the RECEPTIVE FIELD in sensation

A

THE RECEPTIVE FIELD IS THE REGION ON THE SKIN WHICH CAUSES ACTIVATION OF A SINGLE SENSORY NEURON WHEN ITSELF ACTIVATED

30
Q

What does a small receptive field detect

A
  • Small receptive fields allow precise perception and detection of fine detail
31
Q

What does a large receptive field detect

A
  • Large receptive fields allow detection of changes over a wider area
32
Q

What is TWO POINT DISCRIMINATION and what is this related to

A

Minimum distance at which two points are perceived as separate
- Related to size of the receptive field

33
Q

Adelta fibres mediate what type of pain

A

sharp, intense or first pain

34
Q

What are the two types of Adult fibre and what do they detect

A
  • TYPE 1: A-MECHANOHEAT RECEPTORS Noxious mechanical and thermal stimuli
  • TYPE 2: A-MECHANORECEPTORS Noxious mechanical stimuli
35
Q

C fibres mediate what type of pain

A

mediate dull, persistent or second pain:

36
Q

What stimuli do C fibres respond to

A
  • Respond to thermal, mechanical and chemical stimuli(chemical stimuli = inflammatory mediators, PG, BK) - (polymodal)
37
Q

Myelination of C fibres?

A

Unmyelinated

38
Q

Myelination of Adelta fibres?

A

Myelinated

39
Q

Cell bodies of primary afferent neurones are located in … (body and face (for face think nerve innervation))

A

dorsal root ganglia (body) and trigeminal ganglia (face)

40
Q
  • Dorsal horn of the spinal cord is Organised into:
A

Rexed Laminae (I-VII)

41
Q
  • Innocuous mechanical stimuli (Aalpha and Abeta fibres) terminate in lamina X-Y of the dorsal horn
A

III-VI

42
Q
  • Pain and temperature (Adelta and C fibres) terminate in lamina X-Y of the dorsal horn
A

I-II (referred to as the superficial dorsal horn)

43
Q
  • X is the main excitatory neurotransmitter of the dorsal horn
A

Glutamate

44
Q

What is lateral inhibition in the dorsal horn performed by

A
  • Interneurons that connect between different laminae and between adjacent peripheral inputs
45
Q

Lateral inhibition prevents…

A

overlap of receptive fields

46
Q

What is the GATE CONTROL THEORY and what is this due to

A

A dull achey pain response in the dorsal horn can be modulated by activating an Abeta fibre e.g. rubbing on a painful area can reduce pain
Due to lateral inhibition

47
Q

THE DORSAL COLUMN SYSTEM transmits what modality

A

Innocuous mechanical stimuli - fine discriminative touch and vibration

48
Q
  • Information is conveyed from lower limbs and body (below T6) ipsilaterally along the X fasciculus
A

GRACILE

49
Q
  • Information is conveyed from upper limbs (above T6) ipsilaterally along the X fasciculus
A

CUNEATE

50
Q

Fibres of the dorsal column/cuneate and gracile fasciculus?

A

Aalpha and Abeta

51
Q

1st ORDER NEURONS of the dorsal column pathway TERMINATE IN THE X in their respective nucleus

A

MEDULLA dorsal column

52
Q

2nd ORDER NEURONS of the dorsal column pathway DECUSSATE IN THE X

A

Caudal MEDULLA

53
Q

What tract do second order neurons of the dorsal column pathway follow to where

A

CONTRALATERAL MEDIAL LEMNISCUS TRACT from the medulla to the thalamus

54
Q

Where do the 2nd order neurons of the dorsal column pathway terminate (SPECIFIC NUCLEUS)

A

VENTRAL POSTERIOR LATERAL NUCLEUS of the thalamus (VPL)

55
Q

Where do the 3nd order neurons of the dorsal column pathway project from and to

A
  • 3rd order neurons from the VPL nucleus project to the somatosensory cortex
56
Q

Where is there a somatotopic representation of the body in the afferent dorsal column pathway

A

Somatosensory cortex

57
Q

Where is there a topographic representation of the body in the afferent dorsal column pathway

A

In the cuneate and gracilis nuclei in the medulla and the ventral posterior lateral nucleus in the thalamus

58
Q

What are the 2 pathways in THE SPINOTHALAMIC (ANTEROLATERAL) PATHWAY and what are their modalities

A

lateral pathway (pain and temp.) and anterior pathway (crude touch)

59
Q

Where do the 1st order neurons of the the spinothalamic (anterolateral) pathway terminate

A
  • primary afferent (1st order) axons terminate upon entering the spinal cord
60
Q

Where do the 2nd order neurons of the the spinothalamic (anterolateral) pathway project from and to

A

From spinal cord to terminate in the ventral posterior lateral nucleus of the thalamus

61
Q

Where do the 3rd order neurons of the the spinothalamic (anterolateral) pathway project from and to

A
  • 3rd order neurons from the VPL project to the somatosensory cortex
62
Q

Where do the 2nd order neurons of the the spinothalamic (anterolateral) pathway decussate

A

Immediately after synapsing upon entry to the spinal cord

63
Q

What is the spinoreticular system (pain from X to X in X and then to X)

A

Pain transmitted through a pathway from the spinal cord, to the parabrachial area in the brainstem, and then to the limbic system

64
Q

Parts of the brain involved in pain reception? (4)

A

Cortex
Amygdala
Cerebellum
Brainstem

Neuroscience & Mental Health Y2 (18 decks)

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