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Neuro M101A > Module 3 Somatic System > Flashcards

Module 3 Somatic System Flashcards

1
Q

what are the four somatic senses

A

touch, pain, temp, body position

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2
Q

where are somatic receptors located

A

all over the body

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3
Q

what are the types of somatic sensation receptors

A

mechanoreceptors, nociceptors, thermoceptors (also nociceptive thermoreceptors), proprioceptors

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4
Q

where do somatosensory afferents send information

A

skin surface –> central circuits

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5
Q

what is the structure of a pseudounipolar neuron

A

one axon split into two branches; one sends info to PNS, the other to spinal cord (dorsal root ganglion cells)

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6
Q

both touch and pain/temp take the same pathway

A

dorsal horn (ipsilateral) –> 2nd order neurons (decussate) –> contralateral ascent

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7
Q

what are the different types of receptors

A

free nerve endings (nociceptors, thermoreceptors) and encapsulated (most cutaneous receptors

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8
Q

capsule function

A

sensitive to mechanical deformation/activated by temp and chemicals

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9
Q

how do capsules work

A
  • stimuli applied to skin deform or change receptor
  • alters the ionic permeability of the receptor creating generator (receptor) potentials
  • triggers action potentials
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10
Q

what does Merkel’s disks specialize in

A

light touch and tactile discrimination

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11
Q

what does Meissner’s corpuscle specialize in

A

low frequency vibration in glaborous skin (30-50 Hz)

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12
Q

what do Pacinian corpuscles specialize in

A

vibration at 250 - 350 Hz

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13
Q

what do Ruffini’s corpuscles specialize in

A

detecting something slipping through your hands
- skin stretch, sustained pressure

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14
Q

which corpuscles have a small receptive field

A

Merkel and Meissner

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15
Q

which corpuscles have a large receptive field

A

Pacinian and Ruffini

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16
Q

where are Merkel disks located

A

tip of epidermal sweat ridges

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17
Q

Merkel sensory function

A

form and texture perception

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18
Q

Merkel effective stimuli

A

edges, point, corners, curvature

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19
Q

Merkel receptive field area

A

9 mm^2

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20
Q

Merkel innervation density

A

100/cm^2

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21
Q

Merkel spatial acuity

A

0.5mm

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22
Q

Meissner location

A

dermal papillae (close to skin surface)

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23
Q

Meissner sensory function

A

motion detection; grip control

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24
Q

Meissner effective stimuli

A

skin motion

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25
Q

Meissner receptive field area

A

22 mm^2

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26
Q

Meissner innervation density

A

150/cm^2

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27
Q

Meissner spatial acuity

A

3 mm

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28
Q

Pacinian location

A

dermis and deeper tissues

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29
Q

Pacinian sensory function

A

perception of distant events through transmitted vibrations; tool use

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30
Q

Pacinian effective stimuli

A

vibration

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31
Q

Pacinian receptive field area

A

entire finger or hand

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32
Q

Pacinian innervation density

A

20/cm^2

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33
Q

Pacinian spatial acuity

A

10+ mm

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34
Q

Ruffini location

A

dermis

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35
Q

Ruffini sensory function

A

tangential force; hand shape; motion direction

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36
Q

Ruffini effective stimuli

A

skin stretch

37
Q

Ruffini receptive field area

A

60 mm^2

38
Q

Ruffini innervation density

A

10/cm^2

39
Q

Ruffini spatial acuity

A

7+ mm

40
Q

which corpuscles does reading Braille require

A

Merkel & Meissner

41
Q

which corpuscle is the most noisy

A

Pacinian

42
Q

what sensory functions do muscle spindles have

A

proprioception

43
Q

what sensory functions do Merkel, Meissners, Pacinian, and Ruffini corpuscles have

A

touch

44
Q

what sensory functions do free myelinated nerve endings have

A

pain, temperature

45
Q

what sensory functions do free unmyelinated nerve endings have?

A

pain, temperature, itch

46
Q

how is somatosensory information organized

A

into 4 dermatomes (each innervates a certain portion), and into 30 spinal segments

47
Q

how is spinal cord gray matter divided

A

into dorsal horn, intermediate zone, ventral horn

48
Q

what is the function of dorsal columns

A

touch info ascends via dorsal columns

49
Q

shingles cause

A

virus affects 1 spinal segment

50
Q

where do the axons from mechanosensory tract project

A

dorsal horn –> ipsilateral ascent –> 2nd order neurons (medulla); upper body –> cuneate nucleus, lower body –> gracile nucleus; decussation –> contralateral ascent –> VPL thalamus –> primary sensory cortex
- dorsal column medial lemniscal pathway

51
Q

where does the trigeminal pathway enter the brain

A

through the pons

52
Q

what is the trigeminal pathway

A

trigeminal nerve –> pons –> 2nd order neurons –> axons decussate –> ascend contralaterally –> VPM thalamus –> primary sensory cortex

53
Q

where does the primary somatosensory cortex receive input from

A

VP nucleus of thalamus

54
Q

which area receives the most dense connections

A

area 3b

55
Q

where does the ventral posterior complex of thalamus project to

A

primary somatosensory cortex

56
Q

where does area 3a of primary somatosensory cortex project to

A

secondary somatosensory cortex, and area 2

57
Q

where does area 3b of the primary somatosensory cortex project to

A

secondary somatosensory cortex, area 1 (texture), and area 2 (size and shape)

58
Q

where does area 1 of primary somatosensory cortex project to

A

secondary somatosensory cortex

59
Q

where does area 2 of primary somatosensory cortex project to

A

parietal areas 5, 7, and secondary somatosensory cortex

60
Q

where does the secondary somatosensory cortex project to

A

amygdala and hippocampus

61
Q

where do parietal areas 5, 7 project to

A

premotor and motor cortices

62
Q

what kind of information does the primary somatosensory cortex receiveq

A

simple segregated streams of sensory information

63
Q

where does integration occur

A

in posterior parietal cortex

64
Q

what is the posterior parietal cortex involved in

A

somatic sensation, visual stimuli, and movement planning

65
Q

what does damage to the posterior parietal cortex cause

A

inability to recognize objects (agnosia/neglect syndrome)

66
Q

characteristics of cortical somatotopy

A

not continuous, not to scale, relative size of cortex devoted to each body part depends on the density of sensory input

67
Q

how are neurons in primary somatosensory cortex organized

A

in functionally distinct columns
- neurons in each column respond to the same kinds of stimuli

68
Q

what does life without pain cause

A

progressive degeneration of joints, spinal vertebrae, skeletal deformation, infection

69
Q

nociceptor characteristics

A
  • transduction of pain
  • free, unmyelinated nerve endings
  • signal that body tissue is being damaged
70
Q

what are the types of damage detected by nociceptors

A

mechanical (strong pressure, sharp objects), thermal (activates when tissues start to be destroyed), chemical (environmental agents/ those from tissues itself (pH, histamine, etc)

71
Q

types of nociceptors

A

polymodal, mechanical, thermal, chemical

72
Q

hyperalgesia

A

part of damaged skin becomes very sensitive, causes neurotransmitters (CGRP - calcitonin vasodilator) and inflammatory factors (IL -1beta, NGF, TNF - alpha), and histamine to be released
- they bind nociceptors and activate them

73
Q

primary hyperalgesia

A

affects direct site

74
Q

secondary hyperalgesia

A

affects area around direct site

75
Q

bradykinin function

A
  • Product of enzymatic breakdown of kininogen
  • Binds and depolarizes nociceptors
76
Q

prostaglandins function

A
  • Generated by enzymatic breakdown of lipid membrane
  • Increase the sensitivity of nociceptors to other stimuli
77
Q

substance P function

A

Can be secreted by axons branches in adjacent cells; cause the release of histamine

78
Q

A delta fibers characteristics

A

fully myelinated and responsible for initial pain

79
Q

Cfiber characteristic

A

long-lasting, less severe pain

80
Q

type I A delta fibers

A

low threshold for mechanical and chemical stimulation but high threshold for temperature

81
Q

type II A delta fibers

A

high threshold for mechanical and chemical stimulation but low threshold for temperature

82
Q

what do C fibers respond to

A

all stimuli with subtypes with preference for heat/chemical stimuli

83
Q

referred pain

A

pain we feel in different parts of the body with different source (angina, appendicitis)

84
Q

what is the anterolateral pathway

A

nociceptive afferents –> dorsal horn –> second order neurons in dorsal horn –> decussation and contralateral ascent via anterolateral tract

85
Q

rexed lamina pathway in anterolateral pathway

A

C fibers –> dorsal horn –> second order neurons layer 1 –> contralateral transmission to brain

86
Q

A delta fibers pathway

A

layer 1 –> layer 5 –> contralateral transmission –> brain

87
Q

why does cross-talk occur (referred pain)

A

layer 5 of the rexed lamina receives cutaneous info as well as visceral nociception info

88
Q
A

Neuro M101A (9 decks)

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