Somatosensation Flashcards
1
Q
Exteroception
A
sense the external world, information about the external world
2
Q
Proprioception
A
sense of position and movement, knowing where our body is in space
3
Q
Interoception
A
sense of internal world, physiological status, how hungry I am or full, emotions and social kind of thoughts
4
Q
Somatosensory receptors:
A
inform us about objects in our external environment through touch and about the position and movement of our body parts
5
Q
how does external stimulus get to the CNS
A
Stimulus > Receptor (generator) potential > the receptor make a local potential, which means coding that stimulus, which then leads to AP that fire into the CNS
6
Q
what is needed to activate Somatosensory receptors
A
stimulus
7
Q
Thresholdto activate Somatosensory receptors
A
easy or hard to activate
8
Q
somatosensory receptors adaptive response
A
does it tell you continually that you are holding a glass, or do you have to remember that you are holding the glass
9
Q
Low threshold mechanoreceptors
A
discriminative touch (spatial and temporal acuity high)
10
Q
High threshold mechanoreceptors
A
ouch
11
Q
Thermal receptors
A
warm and cool
12
Q
Proprioceptors
A
body and limb position, movement and force
13
Q
Nocioceptors
A
noxious mechanical, chemical, thermal (pain receptors)
14
Q
Polymodal receptors
A
discomfort, itch, hurt (uncomfortable but not descriptively describing it)
15
Q
three types of Low threshold mechanoreceptors
A
RA: rapidly adapting
SA: slowly adapting
PC: Pacinian Corpuscle
16
Q
RA: rapidly adapting
A
On and off, responds to the change in the stimulus (no sustained)
17
Q
SA: slowly adapting
A
SA receptor responds to steady state of the stimulus
- Holding a glass – continually tells you (sustained)
18
Q
PC: Pacinian Corpuscle
A
responds to oscillation of the stimulus, vibration
19
Q
Low threshold mechanoreceptors in the skininclude
A
RA type 1 [RAor RAI], Meissner corpuscle
RA type II [RAII], Pacinian corpuscle
SAI, Merkel’s disk
SAII, Ruffini ending (not clearlyknown in humans)
20
Q
RA type 1 [RAor RAI] other name
A
Meissner corpuscle
21
Q
RA type II [RAII], other name
A
Pacinian corpuscle
22
Q
SAI, other name
A
Merkel’s disk
23
Q
SAII, other name
A
Ruffini ending (not clearlyknown in humans)
24
Q
RAI and SAI properties
A
have very small, well-defined receptive fields: detecthigh acuity of touch; useful for detecting fine detail or texture ofobjects
25
Receptive field
area of skin that results in a consistent response from the neuron when stimulated with the appropriate stimulus
26
Small RF are better with what kind of details
Better with discriminative details
27
RAII properties
have large receptive fields with most sensitive central area and a less sensitive surround; respond to fine vibrations of skin; useful for manipulating a tool or utensils, detection of fine textures
28
SAII properties
have large receptive field with directional preferences coded by groups of receptors; this may be coded by SAIs as well
29
Does the Density of RAI and SAI increase or decrease as we get to the tip of our fingers
increase at we get to the tip of our fingers
30
Discriminative touch is based on what properties of receptor fields
on small receptor fields and the density of these receptors
31
Discriminative active touch
is a process by which humans actively seek tactile information; gather information by engaging in the environment
32
nocioceptor receptor description
Receptors described as free nerve endings
33
Peripheral pain afferents are made of what kind of fibers
small fibers, A delta and C fibers
34
Peripheral pain afferents project to
Neurons in the outer layers of the dorsal horn:
marginal zone and substantia gelatinosa
Wide dynamic range (WDR) neurons in the nucleus proprius.
35
from the dorsal horn where does the pain stimulus travel
neurons project axons into the spinothalamic tract on opposite side of spinal cord and ascend to communicate to neurons in the thalamus and onto the cortex
36
What do WDR neurons receive
large fiber afferent, mechanoreceptor inputs, in addition to small fiber afferents
send this information to a third order neuron in the thalamus
37
Pain afferent receptors fields
have small receptive fields in the periphery
38
Pain stimuli lead to neuroplastic changes in pain afferents - what kind of change is seen
heightened sensitivity of peripheral receptors and dorsal horn neurons
a rapid expansion of their receptive fields.
39
Neurons in brainstem nuclei of the midbrain periaqueductal grey, pons and medulla, nucleus raphe magnus respond to pain fibers by doing what
releasing endogenous opiate
40
what happens when pains activates the neurons of the nucleus raphe magnus
Descending response to the dorsal horn
Descending projection to the opiate interneuron (enkephalin) in the substantia gelatinosa of the spinal cord- this blocks or alter the pain response
Modulating the incoming pain information
41
what is Kinesthesia
the ability to sense the position and location and orientation and movement of the body and its parts.
Without vision
42
what contributes to Kinesthesia
Muscle proprioceptors, joint receptors, cutaneous receptors, vestibular system
43
Muscle proprioceptors
muscle sense of moving, tension and effort
44
two things that contribute to Muscle proprioceptors
Muscle spindles
Golgi Tendon Organs (GTO)
45
Muscle spindles other name
intrafusal
46
Muscle spindles location
embedded in skeletal muscle
Parallel with muscle
47
What does the Muscle spindles tell us
signals change in muscle length, and rate of change in muscle length.
Muscle receptor of motion, force, and effort
48
Each muscle spindle has three elements
Intrafusal muscle fibers
Sensory [afferent] fibers
Motor axons
49
Intrafusal muscle fibers in muscle spindles
contractile fibers in the spindle itself
50
two types of Intrafusal muscle fibers in muscle spindles
Central equatorial
Polar ends
51
what kind of tissue is the Central equatorial region
non-contractile region
52
what kind of tissue is the Polar ends
contractile region, connected to extrafusal muscle
53
Sensory [afferent] fibers of muscle spindle are connected to what region
connected to the non-contractile central regions (central)
All of the sensory info comes from the central region
54
Motor axons going to the muscle spindle connect where
to the polar contractile regions (both ends) of intrafusal muscle fibers.
– things coming back to the spindles
55
Different types of fibers within one muscle spindle
Nuclear chain
Nuclear bag
56
two kinds of Nuclear bag
Static nuclear bag
Dynamic nuclear bag
57
Static nuclear bag properties
static length of muscle
how long I am right now
58
Dynamic nuclear bag responds to what
rate of change/velocity of muscle lengthening, will recognize a stretch
59
Nuclear chain properties
nuclei are arranged in a row/chain
responds to static length of muscle
60
Nuclear bag propties
nuclei are in the middle of the fiber
61
Sensory/afferent fibers going to the muslce spindle
Primary: Ia afferent (large axon) connects to center/equatorial regions all 3 fibers;
Secondary: type II afferents (medium axon) connected to region adjacent to center; only connects to static nuclear bag and nuclear chain
62
Primary and secondary afferent fibers endings signal what from the muscle spindle
steady state length of muscle - the length of the muscle
63
Primary ending 1a: very sensitive to what (muscle spindles)
velocity of stretch
The rate of change in length
Quick stretch of muscle - the Ia afferent signals the abrupt change, enables quick corrective actions (the change is occurring quickly)
64
alpha-gamma co-activation
The process of simultaneous activation of alpha and gamma motor neurons in a voluntary,
Is critical to keep the spindle sensitive and ready to sense stretch
If the above did not occur, the spindle would collapse in an actively contracting muscle
65
what do Alpha motor neurons do
send efferent axons to contract extrafusal muscle fiber
66
What do gamma motor neurons do
in a voluntary contracting muscle, gamma motor neurons are activated to contract intrafusal muscle fibers.
67
two types of gamma efferent
Dynamic gamma motor neurons
Static gamma motor neurons
68
Static gamma motor neurons
Static gamma motor neurons innervate Static Nuclear Bag fibers and Nuclear chain fibers.
69
Dynamic gamma motor neurons
Dynamic gamma motor neurons innervate intrafusal fibers of the Dynamic Nuclear Bag fibers
70
H-reflex
The electrical equivalent to a monosynaptic reflex
71
the H reflex can be altered by what
the state of the ventral horn
Reduced from standing to walking to running: if I am standing on one leg my natural response would not be a kick because that is unstable
72
what happens toe GTO when the muscle is in stretch
leads to squeeze of the GTO when the muscle is stretch
73
GTO location
in the tendon at musculotendinous junction
in series with the muscle
74
what does GTO tell you
Tell you the force of contraction
Golgi tendon organ provides a continuous indication of the force of contraction and changes in force.
75
GTO is innervated by afferents called
Group (type) Ib fibers
76
Group (type) Ib fibers location
have specialized endings that weave in between the collagen fibers
77
Group (type) Ib fibers signalling
Contraction of muscle pulls on tendon that stretches the tendon organ and compresses the Ib afferent endings
Ib inhibits the motor neuron that activate this muscle – tries to protect you from overusing the muscle
78
Two major ascending sensory systems to conscious perception
spinothalamic/anterolateral column
Dorsal column
79
Two major ascending sensory systems carry what kind of infomation
Have unique information
80
Spino/AL carries what info
pain and temp (touch)
81
Dorsal column carries what info
jt position, vibration and discriminative touch information (touch)
82
dorsal column pathway
First neuron in the DRG medulla (crossed in the brainstem) thalamus somatosensory cortex
83
Spino/AL pathway
DRG crosses the spinal cord thalamus cortex
84
unconscious tracts
Ventral spinocerebellar tract, VCST
Dorsal spinocerebellar tract, DCST
85
Ventral spinocerebellar tract, VCST
role in ‘motor copy', information about ventral horn activity, e.g., motor commands sent to the muscles.
Enables adjustments to motor plan while moving …
86
Dorsal spinocerebellar tract, DCST
large fiber afferent information contributes to unconscious perception of movement, position and effort and terminates in cerebellum
87
Dermatome
area of the skin and subcutaneous tissues that is served by a single spinal nerve root
88
Corticothalamocortical loop
mechanism of directing attention to some things and not others; a binding of neurons in the loop attended to
89
Anterior cingulate role
the final decision making in the cortex, deciding if you are going to wait or move (final decision to move)
90
The insular cortex
has a lot to do with self awareness, understanding your internal phys and social and emotional states
91
Anterior insular cortex and anterior cingulate keep a record of what
keep a record of your life
If there was a time in your life that were emotional – these times will get magnified in the AI and AC
This is a reason for the memory that make is feel good
