wk 10 SP

Question 1

Area and weight of skin

Answer 1

1.82 m^2

Weight 5kg

Question 2

• Two types of skin

Answer 2

Glabrous – palms of hands and feet

Hairy – everywhere else

Question 3

4 senses in skin

Answer 3

touch (mechanical )
pain
temperature
body sense (proprioception)

Question 4

4 different tactile receptors in skin

Answer 4

Merkel’s disc
Meissner corpsucle
Ruffini organ
Paccinian corpuscle

Question 5

Merkel’s disc
responds to what

Answer 5

Fine details e.g. braille

Question 6

Meissner corpuscle responds to what

Answer 6

Flutter (e.g. objects slipping through fingers)

Question 7

Ruffini organ responds to what

Answer 7

stretching (due to picking up something)

Question 8

Paccinian corpuscle responds to

Answer 8

vibration, fine texture

Question 9

Receptive fields…

Answer 9

The area of skin
that a particular
cell receives
information about

Question 10

Paccinian corpuscles have
_______ receptive fields than Meissner’s corpuscles

Answer 10

larger

Question 11

Active touch –

Answer 11

active exploration of environment

Question 12

Passive touch

Answer 12

– body is stationary

Question 13

Advantages of active touch

Answer 13

More parts of body contact object
* You can search for the most diagnostic
parts of objects to feel
* Kinesthetic senses are also engaged

Question 14

different cues when percieving texture

Answer 14

Spatial cues – bumps and grooves, when finger is stationery or moving

• Temporal cues – only when move finger across surface

– Paccinican corpuscles – adaptation to high frequencies impairs performance

– Can perceive texture via a tool

Question 15

evidence that there is a difference between recognising an object through touch and recognising where the object is via touch

Answer 15

brain imaging shows
activity in primary and secondary somatosensory cortex when asked WHAT object was

activity in superior parietal areas when asked WHERE object was

Question 16

Top down influences on touch

Answer 16

must update as move body position

Emotional effect - e.g. same sensation may be pleasant or unpleasant depending

Expectation - e.g. surprise tickling

Question 17

pain receptors called

Answer 17

nociereceptor

Question 18

2 types of pain

Answer 18

fast pain , slow pain

same stimulus can activate both systems

Question 19

A delta fibres (type of pain)

Answer 19

fast pain (sharp)
pin prick, pinches, extreme temperature

are myelinated

Question 20

C fibres (type of pain)

Answer 20

slow pain (dull) - many types of pain,

even mild stimulation can be pleasurable

not myelinated

Question 21

pain is more than receptor activity e.g can be affected by

Answer 21

a mental state e.g. battlefield analgesia

Occour in absence of stimulation e.g. phantom limb pain

be affected by attention

Question 22

Gating of pain in the spinal chord influences degree to which painful info reaches the brain,

pain can be reduced by

Answer 22

non-painful tactile inputs e.g. massage, rubbing

Top down input, expectations

Question 23

Proprioception

Answer 23

Where your body is in space
- Signals from muscles

Also can use other modalities – vestibular system, tactile receptors etc.

Also Kinesthesis – movement of the limbs in space

Question 24

A new receptor discovered in
2002

Answer 24

• Patient like Ian
  Waterman
• Lost other senses of
  touch
• Could still feel pain,
  temperature and enjoy
  being cuddled
• CT (C Tactile)