3.2 Touch and Pain

Question 1

Touch

Answer 1

largest sensory system
most complex sense
ALL about survival

Question 2

proprioperception

Answer 2

awareness of own body 
breaks into 4 categories: 
1. temperature 
2. kinaesthetic (muscles)
3. vestibular (motion)
4. Pain

Question 3

Skin

Answer 3

stimulus area for touch but varies depending (ie: pressure, damage, temp, etc)

Question 4

Hairy Skin

Answer 4

Main skin
Epidermis (outer): Dead cells
Dermis (middle): makes new cells
Hypodermis (subcutaneous): contains nerve endings

Question 5

glabrous skin

Answer 5

non hairy skin
palms, sole etc
thicker outer layer
more complex receptors (as its how we explore the world)

Question 6

Receptor types

Answer 6

free nerve endings and encapsulated endings

differences in shape, size, organization (suggests functional specialization)

Question 7

Specificity theory on skin sense

Answer 7

each receptor is responsive to one type of stimulus. evidence suggests this isn’t true

Question 8

pattern theory on skin sense

Answer 8

pattern of nerve impulses determines sensation (coding)

Question 9

Melzack and Wall Theory

Answer 9

blended theory of skin
each receptor can convert particular kind of stimulus into particular types of impulses

hard to support for/ find evidence

• Response to wide variety of stimulus
• Responds as much to Dif stimulus but in Dif patterns

Question 10

touch pathways

Answer 10

starts at skin then splits into two Dif systems at spinal cord: spinothalamic and lemniscal

both end up in somatosensory cortex

contralateral connection

Question 11

spinothalamic pathway

Answer 11

pain pathway
small nerve fibres
poor localization

Question 12

lemniscal pathway

Answer 12

large/fast nerve fibres

precise localization

Question 13

touch

Answer 13

pressure on skin

several difference receptors

Question 14

types of touch receptors

Answer 14

pacinian corpuscles, Rapidly adapting, and 2 slow adapting

Question 15

Pacinian corpuscles

Answer 15

encapsulated nerve ending
onion-like: 70 layers
sensitive to changes in stimulation but not good with sustained

ONSET/OFFSET sensitivity

Question 16

Rapid adapting and one slow adapting

Answer 16

small receptive field with distanct borders

Question 17

pacinian corpuscles and one slow adapting

Answer 17

large receptive field with non-distinct borders

Question 18

threshold for touch

Answer 18

homunculus (more space in brain = greater sensitivity)

Question 19

passive touch

Answer 19

placing object on skin
absolute threshold: smallest detectable

Studied using: von frey hairs (experiment by Weinstein showed women were more sensitive to touch)

Most sensitive: soles of feet
Least sensitive: calf

Question 20

two point discrimination threshold

Answer 20

how to measure threshold of passive touch

Measuring ability to notice 2 points are 2 points (pull them further and further apart from eachother)

Question 21

active touch

Answer 21

exploring through touch
Haptic perception: ID through touch
assess lateralization of function (dichhaptic stimulation)_
generally a lower threshold than passive

Question 22

lateralization of function studied through touch

Answer 22

touch with right hand: verbal ID (Left hemisphere)

touch with left hand: functional ID (right hemisphere)

Question 23

TOUCH ADAPTATION

Answer 23

NOT DUE TO FATIGUE in RA + PC (better with onset offset)

it is due to fatigue in Sa

Question 24

Pain phenomena

Answer 24

perception of tissue damage
sensory and EMOTIONAL component
internal stimulation

Question 25

threshold of pain

Answer 25

depends on senstiivty criterion and body part

Question 26

pain points

Answer 26

more pain points means lower threshold (Higher sensitivity) and not related to absolute threshold

Question 27

Pain tolerance

Answer 27

complicates the identification of thresholds due to individual differences

Question 28

pain adaptation

Answer 28

only mild | hot water up to 46 degrees

Question 29

theories on pain perception

Answer 29

specificity: specific pain receptors pattern theory: specific patterns of stimulation ignores psychological aspects (emotion) and physiological (no pain receptor)

Question 30

gate control theory of pain

Answer 30

pain is an interaction between neural fibres and the brain Transmission cells: pain info sent to brain Neural fibers: affect substantia gelatinosa (GATE) large fibres stimulated = gate closed = perception of pain decreases small fibres stimulated = gate open = perception of pain increases Also controlled by descending inhibitory control (brain top down)

Question 31

temperature sense

Answer 31

separate from touch | not mechanical pressure its about air temperature

Question 32

cold air

Answer 32

blood vessels on surface shrink (vasoconstriction) shivering leads to body warming

Question 33

warm air

Answer 33

blood vessels on surface get bigger (vasodialation) and sweating leads to body cooling

Question 34

thresholds of temperature

Answer 34

different for cold and hot | cold spots and warm spots on skin

Question 35

specificity theory of temperature

Answer 35

coded in nervous system by receptors similar to touch warm: increases firing rate (to encourage cooling) cold: decreases firing rate (to encourage warming)

Question 36

absolute threshold of temp

Answer 36

none, only difference because different areas on body have Dif sensitivity warmth: forehead (least: arms, chest, shoulders) cold: trunk (Least: arms, legs)

Question 37

threshold of temp affected by:

Answer 37

size of area of skin exposed, current skin tem[, time of day, phase of menstrual cycle, stress

Question 38

thermal adaptation

Answer 38

only mild temperatures | can adapt completely between 29 and 37