Skin And Touch

Question 1

What does the primary somatosensory cortex produce

Answer 1

Representations of touch, temp, pressure, proprioception and pain

Question 2

What do the medial and superior regions of the primary somatosensory cortex represent

Answer 2

The orderly projection of bodily nerve human homonculus
Somatopically organised
Pen field and Rasmussen 1950

Question 3

What are animal homonculus’ like

Answer 3

Variation in representation between species related to needs and primary uses

Question 4

Describe Woolsey et Al

Answer 4

Monkey homonculus

Largest representation of facial and feet nerves

Question 5

How are rat whiskers organised on the homunculus

Answer 5

Specific receptors

Interactions produce specific neuronal activity

Question 6

What is the somatosensory pathway

Answer 6

Ap from sensory to spinal cord
To medulla - pass via decussation to opposite side of thalamus
Thalamus to cerebral cortex

Question 7

What are afferent nerves

Answer 7

Send sensory info from sensory PNS to CNS

Distinguish by myelin stun and diameter - determine conduction velocity

Question 8

Classification of senses

Answer 8

Specialised specific or general found in many areas of the body

Question 9

Sub classification of types of receptors

Answer 9

Cutaneous

• muscles, joints, tendons and cutaneous tissue
• kinaesthesis - position and movement

Interoceptors/visceral

• internal body organs
• function and respiration

Question 10

Sub classification of cutaneous (1 type of receptor)

Answer 10

Slow unencapsulated

• temp/pain/pressure
• always respond
• a-delta & c-sensory afferent nerves
• always respond

Fast encapsulated
- freq/pressure
-alpha/beta sensory afferent nerves
Detect sudden input

Question 11

Distribution of cutaneous receptors

Answer 11

Hairless

• sweat glands
• corpuscles
• dense in receptors

Hairy

• sebaceous glands
• hair follicles
• not dense in receptors

Question 12

Cutaneous receptive fields

Answer 12

Every neutron has slightly different sensitivity

Receptive fields overlap

Question 13

Describe the meisseners corpuscle

Answer 13

Rapid adaptation
Small receptive field

Respond to light touch

Question 14

Describe the parcinian corpuscle

Answer 14

Rapids adaptation
Large receptive field

Detect vibration and pressure

Question 15

Describe the merkels disks

Answer 15

Slow adaptation
Small receptive field

Respond to pressure and position

Question 16

Describe riffini bulbs

Answer 16

Slow adaptation
Large receptive field

Respond to skin stretch

Question 17

Define adaptation speed of receptors

Answer 17

Time taken to return to normal firing rate after receiving a stimulus

Question 18

Describe bolanowski et Al

Answer 18

4 basic dimensions of touch 
Vibration 
Flutter
Pressure
Sensitivity to temp 

Interaction make diff perceptions
Rough/smooth
Hard/soft
Viscosity (fluid)

Question 19

Where is the primary soma to sensory cortex located

Answer 19

Post central gurus