Week 5 (Touch, Pain and Temperature)

Question 1

What are the mechanical senses?

Answer 1

-Vestibular sensation
-Somatosensation

Question 2

What is vestibuation

Answer 2

Vestibular system made up of receptors in inner ear that respond to body position & movement/tilt of the head

This information is used alongside our other senses in order to perceive what is happening

It also aids balance, which is why inner ear infections result in dizziness and loss of balance.

Question 3

What does the vestibular system consist of?

Answer 3

The semicircular canals
The Otolith organ

Question 4

The Semicircular canals

Answer 4

-3 canals filled with fluid (endolymph) with hair cells in it
-Movement causes endolymph to move against hair, bending the hair*
-Oriented on 3 planes – comparative stimulation gives brain information about movement of head

Question 5

The Otolith organ

Answer 5

-These sends messages about our position in 3D space
-They are sensitive to acceleration, deceleration, & direction changes
-Comprise Utricle and Saccule – different orientations
similar to the endolymph but they are glutinous

Question 6

What are the key aspects of somatosensation?

Answer 6

-Hapsis (fine touch, pressure)
-Kinesthesis, vestibular (movement, position & spatial orientation/ balance)
-Proprioception (awareness of our body in space)
-Temperature
-Pain

Question 7

What are stimulus inside and outside of the body called?

Answer 7

Inside: Interoceptors and Proprioceptors
Outside: Exteroceptors

Question 8

What are the two types of skin?

Answer 8

Hairy and glabrous (hairless)

Question 9

What is hapsis a fancy word for, (or haptic/ tactile receptors)

Answer 9

The sensation of pressure

Question 10

What are the different layers of skin called?

Answer 10

Epidermis, Dermis & Subcutaneous tissue.

Question 11

The Epidermis

Answer 11

Top layer, contains cells that produce pigment and protect immune system.

Question 12

The Dermis

Answer 12

Contains much of our nerve endings, oil and sweat glands, and hair follicles.

Question 13

Subcutaneous tissue

Answer 13

Fat, connective tissue, blood vessels

Question 14

Hair receptors

Answer 14

Dendrite attached to hair on your skin

-As an object moves across the skin, these hairs move, sending a nerve impulse
-Detect direction because specialised receptors for each direction (e.g. leftwards)

Question 15

Cutaneous Receptors

Answer 15

encapsulated (surrounded by a capsule)
or unencapsulated (includes free nerve endings).

Question 16

Free nerve endings in the skin

Answer 16

-most common in skin; different forms
-Dendrite of sensory neuron
Polymodal (not specialised):
-Sensitive to painful stimuli, to hot and cold, and to light touch.
-Slow to adjust to a stimulus

Question 17

What are the 4 primary tactile mechanoreceptors in the skin?

Answer 17

-Pacinian Corpuscles
-Ruffini’s Corpuscles
-Merkel’s disks
-Meissner’s corpuscles

Question 18

Pacinian Corpuscle

Answer 18

-The specific capsule involved in pressure detection; important for detecting deep touch and vibration
-Rapidly-adapting (changing stimuli)
Involves both superficial & deep layers and hair

Question 19

Ruffini’s Corpuscle

Answer 19

-Also found deep in dermis and subcutaneous tissue
-Also found in both glabrous and hairy skin

-Sensitive to stretching/sustained deep touch
-Slow adapting

Question 20

Merkel’s Disk

Answer 20

-Unencapsulated
-Found in epidermis and deeper
-Also found in both glabrous and hairy skin

-Tonic receptors: sustained light touch
Slow adapting

Question 21

Meissner’s Corpuscle

Answer 21

-Encapsulated receptor; found high within dermis
-Particularly found in glabrous skin, and finger pads
-Rapidly-adapting, sensitive to light touch (changing stimuli)
-Sensitive to shape and textural changes in exploratory and discriminatory touch (e.g., Braille)

Question 22

Special receptors that detect temperature and pain.

Answer 22

Nociceptors detect pain and temperature
Thermoreceptors- separate hot and cold

Question 23

Proprioception (6th sense)

Answer 23

-Location and movement of body (e.g. that sense of awareness of where limbs are)

-Proprioceptors are encapsulated nerve endings, sensitive to the stretch of muscles/tendons and joint movement
-Fastest fibres

Question 24

What are the 2 systems of receptors

Answer 24

Rapidly adapting and slowly adapting receptors

Question 25

Rapidly adapting receptors

Answer 25

(stimulated at beginning and end)
-Produce bursts of action potentials
-Involved in detecting discriminate touch (Meissner’s corpuscles) and fluttering (Pacinian corpuscles; faster)

Question 26

Slowly adapting receptors

Answer 26

(tells that stimulus is still occurring; detect steady pressure)
-Light pressure: E.g. Merkel’s receptors and hair receptors
-When clothing is on, only these remain active
-Firmer pressure: Ruffini Corpuscle = vibration due to stretching (Ruffini corpuscles)

Question 27

Different travel speeds

Answer 27

Haptic & proprioception carried by large, well-myelinated axons (faster, for rapid response)
‘Type A fibres’
Nociceptive info
Temperature, pain, tickle, itch: carried by smaller axons, with little or no myelination
(occurs for long time, so don’t need rapid response)
‘Type C fibres’

Certain fast pain carried by myelinated ‘Type A fibres’
Still slower than haptic/proprioceptive axon fibres

Question 28

How fine touch and crude touch travels

Answer 28

-(Fine) Touch information ascends spinal cord ipsilaterally via the Dorsal Column Medial Lemniscal Pathway

-Nociceptive (and crude touch) information ascends contralaterally via the Spinothalamic Pathway(s)

Question 29

Haptic proprioception route to the brain

Answer 29

-Axons for haptic-proprioception located in dorsal portion of spinal cord
-Synapse at base of brain in dorsal-column nuclei
-These then cross to other side of brainstem through medial lemniscus (in medulla)
-Synapse in ventrolateral thalamus
-Sends most axons to somatosensory cortex but some to motor cortex too

Question 30

Nociception route to the brain

Answer 30

Axons for nociception synapse in dorsal part of spinal cord’s grey matter
Neurons send axons to ventral part of other side of spinal cord*
Some also send information to the somatosensory cortex*
Conscious, sensory aspects of pain
Also to insular and anterior cingulate cortex

Question 31

Where is the primary somatosensory cortex located?

Answer 31

The post central gyrus