Lecture 10 Flashcards

1
Q

Area of skin

A

1.8 m^2

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2
Q

Weight of skin

A

5kg

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3
Q

What is skin?

A

Largest sense organ in the body

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4
Q

Two types of skin

A

Glabrous and hairy

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5
Q

Where is glabrous skin found?

A

Palms of hands and feet

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6
Q

Where is hairy skin found?

A

Everywhere but hands and feet

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7
Q

Physiology of skin senses

4 stages

A

1) stimulus contacts skin
2) receptor in skin fires
3) signal travels to the brain via spinal cord
4) signal reached somatosensory cortex on opposite side of the body

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8
Q

What 4 senses do skin receptors give sense to

A

Touch (mechanical stimuli)
Pain
Body sense (proprioception)
Temperature

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9
Q

4 types of tactile receptor

A

Merkel’s disc
Meissner corpuscle
Ruffini organ
Paccinian corpuscle

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10
Q

Merkel’s disc responds to

A

Fine details (e.g., braille)

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11
Q

Meissner corpuscle responds to

A

Flutter (like an object slipping through fingers)

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12
Q

Ruffini organ responds to

A

Stretching

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13
Q

Paccinian corpuscle responds to

A

Vibration, fine texture (like using a tool)

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14
Q

Why do we have multiple receptor types

A

Many receptors allows us to detect many types of information

A single stimulus can activate many different receptor systems

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15
Q

Receptive fields

A

The area of skin that a particular cell receives information about

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16
Q

Do meissener’s or Paccinian corpuscles have larger receptive fields?

A

Paccinian

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17
Q

Two point threshold

A

The smallest separation of 2 separate but adjacent points that just produces two distinct impressions of touch

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18
Q

fingertip 2 point threshold

A

2 mm

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19
Q

arm 2 point threshold

A

3.5 cm

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20
Q

what stops two points from being discriminated|?

A

both points of pressure are within the same receptive field

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21
Q

where are we most sensitive?

A

lips, hands and face

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22
Q

fovea of the skin, why is it named this?

A

fingertip

most receptors

23
Q

what happens to fingertip with experience

A

acuity can change

24
Q

active touch

A

active exploration of environment

25
Q

passive touch

A

body is stationary

26
Q

advantages of active touch

A

more parts of your body are in contact with the object

you can search for the most diagnostic parts of objects to feel

kinaesthetic senses are also engaged

27
Q

cues in perceiving texture

A

spatial

temporal

28
Q

spatial cues in perceiving texture

A

bumps and grooves when finger is stationary or moving

29
Q

temporal cues when perceiving texture

A

only when moving finger across a surface
paccinian corpuscles: adaption to high frequencies impairs performance
can perceive texture via a tool

30
Q

tactile agnosia

A

cannot identify objects by touch but have no problems with spatial processing (WHERE not what)

31
Q

tactile extinction

A

the. failure to detect a stimulus only in the presence of. another stimulus to certain parts of the body
no problems in object recognition (WHAT not where)

32
Q

activity when determining what object was

A

activity in primary and secondary somatosensory cortex

33
Q

activity when determining where object was

A

activity in superior parietal areas

34
Q

top down influences on touch

A

must update as move body position

emotional effect of touch- same sensation may be pleasurable or unpleasant

expectation vs surprise (tickling)

35
Q

illusions of touch

A

Aristotle’s illusion

cutaneous rabbit illusion

36
Q

affect of the cutaneous rabbit illusion

A

activity in the primary somatosensory cortex as if more points than physically touched had actually been stimulated

37
Q

why cant you tickle yourself ?

A

can predict your own actions

same touch rates as more ticklish when produced by an experimenter rather than self

38
Q

nociceptor

A

receptors for pain

39
Q

two types of pain

A

A delta fibres- fast sharp pain

C fibres - slow dull pain

40
Q

a delta fibre pain examples

A

pin prick, pinches, extreme temperature

41
Q

C fibres pain examples

A

many types of pain

mild stimulation can be pleasurable

42
Q

can one stimulus activate both pain systems

A

yes

43
Q

what can pain be affected by?

A

a persons mental state

attention

44
Q

an example of pain in the absence of stimulation

A

phantom limb pain

45
Q

gating of pain in the spinal cord influences…

A

the degree to which painful information reaches the brain

46
Q

what can pain be reduced by?

A

non-painful tactile inputs (massage, rubbing)

top down input (expectations etc.)

47
Q

what is a phantom limb?

A

after a limb is amputated and a patient feels a phantom limb in its place
there is no external stimulus but the patient still perceives the limb
many patients feel phantom arms/ hands when touched on the face: missing hand is still represented in the brain

48
Q

what is proprioception?

A

where your body is in space

49
Q

what is proprioception reliant on?

A

signals from muscles

vestibular system, tactile receptors…

kinesthesis`

50
Q

kinesthesis

A

movement of limbs in space

51
Q

IW case study

A

lost proprioception, kinesthesis and touch age 19 from viral infection
learned to compensate using visual system, unable to move if its dark

52
Q

physiological changes in IW

A

lost fast myelinated fibres, retained slow C fibres

53
Q

C tactile

A

pain, temperature, enjoy being cuddled