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Neuro M101A > Module 3 Somatic System > Flashcards

Module 3 Somatic System Flashcards

(88 cards)

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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
Meissner receptive field area
22 mm^2
26
Meissner innervation density
150/cm^2
27
Meissner spatial acuity
3 mm
28
Pacinian location
dermis and deeper tissues
29
Pacinian sensory function
perception of distant events through transmitted vibrations; tool use
30
Pacinian effective stimuli
vibration
31
Pacinian receptive field area
entire finger or hand
32
Pacinian innervation density
20/cm^2
33
Pacinian spatial acuity
10+ mm
34
Ruffini location
dermis
35
Ruffini sensory function
tangential force; hand shape; motion direction
36
Ruffini effective stimuli
skin stretch
37
Ruffini receptive field area
60 mm^2
38
Ruffini innervation density
10/cm^2
39
Ruffini spatial acuity
7+ mm
40
which corpuscles does reading Braille require
Merkel & Meissner
41
which corpuscle is the most noisy
Pacinian
42
what sensory functions do muscle spindles have
proprioception
43
what sensory functions do Merkel, Meissners, Pacinian, and Ruffini corpuscles have
touch
44
what sensory functions do free myelinated nerve endings have
pain, temperature
45
what sensory functions do free unmyelinated nerve endings have?
pain, temperature, itch
46
how is somatosensory information organized
into 4 dermatomes (each innervates a certain portion), and into 30 spinal segments
47
how is spinal cord gray matter divided
into dorsal horn, intermediate zone, ventral horn
48
what is the function of dorsal columns
touch info ascends via dorsal columns
49
shingles cause
virus affects 1 spinal segment
50
where do the axons from mechanosensory tract project
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
where does the trigeminal pathway enter the brain
through the pons
52
what is the trigeminal pathway
trigeminal nerve --> pons --> 2nd order neurons --> axons decussate --> ascend contralaterally --> VPM thalamus --> primary sensory cortex
53
where does the primary somatosensory cortex receive input from
VP nucleus of thalamus
54
which area receives the most dense connections
area 3b
55
where does the ventral posterior complex of thalamus project to
primary somatosensory cortex
56
where does area 3a of primary somatosensory cortex project to
secondary somatosensory cortex, and area 2
57
where does area 3b of the primary somatosensory cortex project to
secondary somatosensory cortex, area 1 (texture), and area 2 (size and shape)
58
where does area 1 of primary somatosensory cortex project to
secondary somatosensory cortex
59
where does area 2 of primary somatosensory cortex project to
parietal areas 5, 7, and secondary somatosensory cortex
60
where does the secondary somatosensory cortex project to
amygdala and hippocampus
61
where do parietal areas 5, 7 project to
premotor and motor cortices
62
what kind of information does the primary somatosensory cortex receiveq
simple segregated streams of sensory information
63
where does integration occur
in posterior parietal cortex
64
what is the posterior parietal cortex involved in
somatic sensation, visual stimuli, and movement planning
65
what does damage to the posterior parietal cortex cause
inability to recognize objects (agnosia/neglect syndrome)
66
characteristics of cortical somatotopy
not continuous, not to scale, relative size of cortex devoted to each body part depends on the density of sensory input
67
how are neurons in primary somatosensory cortex organized
in functionally distinct columns - neurons in each column respond to the same kinds of stimuli
68
what does life without pain cause
progressive degeneration of joints, spinal vertebrae, skeletal deformation, infection
69
nociceptor characteristics
- transduction of pain - free, unmyelinated nerve endings - signal that body tissue is being damaged
70
what are the types of damage detected by nociceptors
mechanical (strong pressure, sharp objects), thermal (activates when tissues start to be destroyed), chemical (environmental agents/ those from tissues itself (pH, histamine, etc)
71
types of nociceptors
polymodal, mechanical, thermal, chemical
72
hyperalgesia
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
primary hyperalgesia
affects direct site
74
secondary hyperalgesia
affects area around direct site
75
bradykinin function
- Product of enzymatic breakdown of kininogen - Binds and depolarizes nociceptors
76
prostaglandins function
- Generated by enzymatic breakdown of lipid membrane - Increase the sensitivity of nociceptors to other stimuli
77
substance P function
Can be secreted by axons branches in adjacent cells; cause the release of histamine
78
A delta fibers characteristics
fully myelinated and responsible for initial pain
79
Cfiber characteristic
long-lasting, less severe pain
80
type I A delta fibers
low threshold for mechanical and chemical stimulation but high threshold for temperature
81
type II A delta fibers
high threshold for mechanical and chemical stimulation but low threshold for temperature
82
what do C fibers respond to
all stimuli with subtypes with preference for heat/chemical stimuli
83
referred pain
pain we feel in different parts of the body with different source (angina, appendicitis)
84
what is the anterolateral pathway
nociceptive afferents --> dorsal horn --> second order neurons in dorsal horn --> decussation and contralateral ascent via anterolateral tract
85
rexed lamina pathway in anterolateral pathway
C fibers --> dorsal horn --> second order neurons layer 1 --> contralateral transmission to brain
86
A delta fibers pathway
layer 1 --> layer 5 --> contralateral transmission --> brain
87
why does cross-talk occur (referred pain)
layer 5 of the rexed lamina receives cutaneous info as well as visceral nociception info
88

Neuro M101A (9 decks)

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