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Neuroscience > Exam Two - Somatosensory Physiology Receptors > Flashcards

Exam Two - Somatosensory Physiology Receptors Flashcards

1
Q

What are sensations?

A

virtual reality, how the nervous system transduces energy into perception

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2
Q

What is feature extraction?

A

what our sensory receptors do, these receptors extract different features of a given stimulus and send it to CNS

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3
Q

What is a general problem for all sensory systems?

A

representing multidimensional stimula with a single language - frequency of action potentials

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4
Q

best stimulus for a specific receptor?

A

adequate stimulus
- sensory receptors are activated by a specific stimuli

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5
Q

transduction

A

conversion of specific aspects of stimulus energy into membrane conductance change, that leads to a graded potential

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6
Q

generator potentials can lead to an…

A

AP

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7
Q

GP are membrane potential changes, that…

A
  • may be summated
  • degraded over time and distance
  • are not sustained
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8
Q

What are two types of GP?

A

1 - receptor potentials
2 - synaptic potentials

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9
Q

Receptor potentials

A
  • local responses that occur at a sensory receptor and in regions of the membrane that ghave only ligand gated channels
  • graded in amplitude and duration
  • proportional to the amplitude and duration of the stimulus
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10
Q

Where do synaptic potentials occur?

A
  • postsynaptic membrane of dendrites, soma, or axon terminals.
  • similar to receptor potentials
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11
Q

________ must reach a portion of the axon that contains voltage gated channels for generation an __________

A

receptor potentials, AP

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12
Q

The portion of the AXON. that is in contact with RECEPTOR does not have “voltage gates” channels, therefore the change in membrane potential is __________ and __________ of the applied stimulus

A

directly proportional with the intensity, duration

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13
Q

What are two types of graded potentials at the synapse?

A

EPSP, IPSP

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14
Q

depolarizing membrane potential = ________, hyperpolarizing membrane potential = _____________.

A

EPSP, IPSP

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15
Q

EPSP is…

A

local
depolarzing
graded
slow
electronic (passive spread and decremental)

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16
Q

__________ have common features with EPSP, both are graded, local, dissipate if AP is not generated.

A

receptor potentials

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17
Q

At the ___ or _________, generator potentials may be summated to the point where the threshold level for an AP is reached.

A

axon hillock, adjacent to sensory receptor (“trigger zone”)

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18
Q

Where is threshold voltage?

A

-55

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19
Q

what are the two types of graded potential summation?

A

temporal and spatial summation

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20
Q

temporal summation

A
  • same stimulus
  • repeated close together in time (high frequency)
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21
Q

spatial summation

A
  • location of synaptic input
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22
Q

What are the 4 basic dimensions of a stimulus/sensation

A

1 - modality
2 - intensity
3 - location
4 - timing

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23
Q

modality

A

what the sensation type is
ex - vision, taste, smell, touch, etc…

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24
Q

submodality

A

quality of stimulus
- color vision
- touch vibration

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25
Q

intensity

A

how much of sensation

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26
Q

What is intensity coded by?

A

frequency code

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27
Q

What is intensity limited by?

A

absolute refractory period

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28
Q

neural mass

A

number of axons activated

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29
Q

location

A

where the sensation originated

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30
Q

receptive field

A

portion of the sensory space that can evoke neuronal responses upon stimulation

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31
Q

precise location

A

overlap of RFs increases ability to discriminate location

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32
Q

_______ increase likelihood of discrimination

A

small RFs

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33
Q

___________ improves discrimination

A

overlap of RFs

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34
Q

Size of RF varies with location, distal to proximal (increase/decrease)?

A

increase

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35
Q

size of RF varies with the density of innervation, distal to proximal (increase/decrease)?

A

decrease

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36
Q

Size of RF varies with stimulus intensity until_________

A

maximum size is reached

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37
Q

timing

A

when the stimulus starts and stops

38
Q

adaptation rate

A

how long receptors continue to generate AP when the probe is in the RF and motionless

39
Q

RA stands for?

A

rapidly adapting receptors

40
Q

RA receptors

A

respond to dynamic aspects of the stimulus (movement: velocity and acceleration)

41
Q

SA stands for?

A

slowly adapting receptors

42
Q

SA receptors

A

respond to static (and dynamic) aspects of the stimulus, respond if the stimulus is there even if its not moving

43
Q

temporal pattern of coding

A

receptors respond to the stimulus onset, duration, offset

44
Q

Absolute threshold

A

feel it or not
- signmoid curve
- 50% of the time patients say they feel stimulation

45
Q

why is using AT problematic?

A

AT changes with emotion state, mood, and distractions

46
Q

differential threshold (JND)

A

minimus difference in stimululation that a person can detect 50% of the time

47
Q

T or F? Differentiating is linear

A

False! It’s not!
It is better at lower intensity, as we go higher, the difference must be much bigger for perception of the difference

48
Q

3 factors for differential threshold: point localization

A

1 - varies with location
2 - best on face and hands
3 - related to RF size

49
Q

Two point threshold is related to….

A

1 - RF size
2 - innervation density
3 - RF overlap

50
Q

How are somatosensory receptors classified? and what are the classifications?

A

classified by what part of the world they perceive
- exteroceptive
- proprioceptive
- interoceptive

51
Q

cutaneous and subcutaneous mechanoreceptors

A

pacinian corpuscle
meissners corpuscle
ruffini ending
merkel cell

52
Q

pacinian corp chart

A

ra, AB, contact vibration

53
Q

meissners corp chart

A

RA AB contact flutter

54
Q

ruffini ending chart

A

SA AB pressure, skin stretch

55
Q

merkel cell chart

A

SA AB pressure, texture

56
Q

muscle, deep mechanoreceptors

A

muscle spindle
golgi tendon organ
joint capsule-mechanoreceptor
stretch-sensitive free endings

57
Q

muscle spindle chart

A

SA Aa muscle length and change in length

58
Q

golgi tendon organ chart

A

SA Aa muscle tension, change in tension

59
Q

joint capsule mechanoreceptors chart

A

SA AB joint angle and rate of change

60
Q

stretch-sensitive free endings chart

A

SA A delta excess stretch or force

61
Q

thermoreceptors and nociceptors

A

cool receptors
warm receptors
mechanical nociceptor
thermal nociceptor (2 types)
polymodal nociceptor

62
Q

cool receptors

A

SA Adelta skin cooling

63
Q

warm receptors

A

SA C skin warming

64
Q

mechanical nociceptor

A

SA Adelta sharp pain (fast pain)

65
Q

thermal nociceptor (2types)

A

RA Adelta burning pain
RA C freezing pain

66
Q

polymodal nociceptor

A

RA C aching, burning pain (slow pain)

67
Q

What are the receptors in glabrous (hairless) skin?

A

meissners corpuscle
merkels disks
pacinian corpuscle

68
Q

what are the receptors in hairy skin?

A

hair-follicle receptor
tactile disk
ruffini ending

69
Q

What stimulus does the pacinian corpuscle respond to?

A

vibration detector
responds to acceleration/deceleration points in skin indentation

70
Q

why is the RF of pacinian corpuscle large?

A

because vibration travels easily through body tissues

71
Q

what is the adaptation rate of pacinian corpuscle?

A

RA rapidly adapting

72
Q

What is the receptive field size of pacinian corpuscle?

A

large

73
Q

What type of fibers are pacinian corpuscles?

A

AB

74
Q

what stimulus does meissner corpuscle respond to?

A

velocity change (ramps of skin movement)
can respond to slow vibrations called “flutter”

75
Q

What type of fibers are meissners corpuscle?

A

AB

76
Q

What is the adaptation rate of meissners corpuscle?

A

RA

77
Q

What is the receptive field size of meissner corpsucle?

A

small!!

78
Q

2 facts about meissner corpuscle you need to remember?

A
  • may contribute to high spatial resolution of fingertips, lips, etc.
  • capsule consists of flattened epithelial cells
79
Q

Ruffini ending respond to what kind of stimulus?

A

responds to velocity ramp (dynamic phase) and the plateau (static phase) of skin indentation
encodes intensity (pressure) really well

80
Q

describe the AP distribution of ruffini endings

A

AP during plateau are evenly spaced but frequency of AP increases with intensity

81
Q

What is the receptive field size of ruffini endings?

A

large! large, stretch sensitive receptive field

82
Q

What is the adaptation rate of ruffini endings?

A

SA

83
Q

What type of fibers are ruffini endings?

A

AB fiber

84
Q

What is special about merkel cells?

A

an epithelial cell that has a synapse with the neuron
obviously the receptor cannot produce APs

85
Q

describe the AP distribution of merkel cells?

A

characteristic irregular discharge pattern during plateau phase

86
Q

What is the receptive field size of merkel cells?

A

very small, punctate receptive field

87
Q

What type of stimulus do merkel cells read?

A

a good intensity response, known as a “pressure receptor”

88
Q

What is the adaptation rate of merkel cells

A

SA

89
Q

What type of fibers are merkel cells?

A

AB fibers

90
Q

______ receptors respond to a given simulus

A

All!! Each receptor extracts a different type of information from the stimulus

91
Q

Describe the pathway from the skin receptor to the brain

A

receptors read stimulus, send it up the the nucleus cuneatus, then to VPL nuclei of the thalamus, and from there to the somatosensory cortex

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