L04: Sensory Sytem (somatosensory)

Question 1

What is the primary sensory i.e first order neurone also known as

Answer 1

Primary afferent

Question 2

Where is the cell body of the first order neurone found

Answer 2

In the dorsal root ganglia

Question 3

Where does the axon of the first order neurone innervate

Answer 3

Receptive field

Question 4

What happens to the first order neurone when it enter the spinal cord

Answer 4

• Splits into 3 : above, below, same spinal level

- Terminates to 2nd order neurone

Question 5

Where does the second order neurone take the information to

Answer 5

Thalamus

Question 6

At the thalamus what happens to the second order neurone

Answer 6

Terminates to give 3rd order neurone

Question 7

Are sensory neurones excitatory or inhibitory

Answer 7

Excitatory

Question 8

What is the common neurotransmitter that sensory neurones release

Answer 8

Glutamate

Question 9

How do we classify axons in the primary afferents

Answer 9

Depending on myelination

Question 10

What are the axons from the skin

Answer 10

A beta
A delta
C

Question 11

What happens to the axon as you go from a beta to c fibre

Answer 11

The axon becomes more unmyelinated

Question 12

What does a beta axons pick up from the skin

Answer 12

Mechanoreceptors

Question 13

What does a gamma axons pick up from the skin

Answer 13

Pain

Temperature

Question 14

What does c axon pick up from the skin

Answer 14

Temperature
Pain
Itch

Question 15

Where does a each axon innervate within its dermatome

Answer 15

Receptive field

Question 16

What is a dermatome

Answer 16

Area of skin innervated by as single spinal root

Question 17

What is an adequate stimulus

Answer 17

The right stimulus which depends on the nerve ending

Question 18

For a signal to be transducer what has to be reached

Answer 18

Threshold

Question 19

What are the ion channels on the nerve endings called

Answer 19

Transduction channels

Question 20

What happens to the tranduction channels which open upon suffice to energy stimulus

Answer 20

Open

Question 21

What happens when the transduction channels open

Answer 21

Positive ions enter to cause depolarisation

Question 22

What is a a graded receptor potential

Answer 22

The size of stimulus that determines the size of action potential e.g large stimulus= large potential

Question 23

When is a signal only sent

Answer 23

When they reach a threshold

Question 24

What is the firing rate of the action potential dependent on

Answer 24

Stimulus strength

Question 25

What are the 2 types of adapting sensory receptors

Answer 25

1) slow or non adapting receptor | 2) fast adapting receptors

Question 26

What happens in a slow or non adapting receptor

Answer 26

Firing is continuous when stimulus is present

Question 27

When is a slow or non adapting stimulus important

Answer 27

When maintaining information about a stimulus is valuable e.g amount of stretch or pain

Question 28

What is the fast adapting receptor

Answer 28

When there is a change in stimulus there is a high rate of firing but firing decreases if the stimulus is maintained

Question 29

When is the fast adapting receptor important

Answer 29

When the stimulus is no longer important e.g (tactile touch) getting dressed in the morning and not being able to feel you clothes on you later on

Question 30

What does a slow adapting receptor detect

Answer 30

Strength of stimulus

Question 31

What does a fast adapting receptor decked

Answer 31

How fast the stimulus is changing

Question 32

What are the 3 types of sensory receptors found in the skin

Answer 32

Mechanoreceptors Thermoreceptors Nociceptors

Question 33

What does mechanoreceptors detect

Answer 33

Touch Pressure Vibration

Question 34

What does thermoreceptors detect

Answer 34

Hot and cold

Question 35

What does thermoreceptors not detect

Answer 35

The Temperature

Question 36

Where is temperature processed

Answer 36

At the brain

Question 37

What does nociceptors detect

Answer 37

Noxious stimulation

Question 38

What are the 2 main layers of the skin

Answer 38

Epidermis | Dermis

Question 39

What is the most superficial layer

Answer 39

epidermis

Question 40

What is the most deep layer

Answer 40

Dermis

Question 41

What are the fibres of mechanoreceptors

Answer 41

A beta fibres

Question 42

What is the structure of mechanoreceptors

Answer 42

Has an apparatus that is comprised of specialised cells

Question 43

What are the 4 types of mechanoreceptors

Answer 43

Merkels receptors Meissners corpuscle Ruffins corpuscle Pacinian corpuscle

Question 44

Which mechanoreceptors are Lund in the superficial layer of the skin

Answer 44

Merkels receptors | Meissners corpuscle

Question 45

What are the mechanoreceptors found in the deeper layers of the skin

Answer 45

Ruffini’s corpuscle | Pacinian corpuscle

Question 46

What type of receptors are merkels receptor

Answer 46

Slow adapting

Question 47

Which cells does the merkel receptor innervate in the skin

Answer 47

Keratocyte

Question 48

What does merkel receptors detect

Answer 48

Skin indentation e.g allows Braille reading

Question 49

What type of receptors are meissners corpuscle

Answer 49

Rapidly adapting sensory receptors

Question 50

What does meissners corpuscle detect

Answer 50

Light touch vibration e.g putting clothes on

Question 51

What does Ruffini’s corpuscle respond to

Answer 51

Lateral movement Stretching Deep touch

Question 52

What type of receptors are pacinian corpuscle

Answer 52

Rapidly adapting receptor

Question 53

What is the stimulus of pacinian corpuscle

Answer 53

Deep touch e.g poking | High frequency vibration

Question 54

How does the pacinian corpus fire ap

Answer 54

When it is squashed it becomes deformed

Question 55

What type of receptors are hair follicle receptors

Answer 55

Rapidly adapting receptors

Question 56

What does the hair follicle receptor detect

Answer 56

Light touch

Question 57

What are the cutaneous thermoreceptors like in their structure

Answer 57

With bare nerve endings | Does not have a specialised apparatus like the mechanoreceptors

Question 58

What type of receptors are cutaneous thermoreceptors

Answer 58

Slow adapting receptors

Question 59

What is the 2 stimulus for thermoreceptors

Answer 59

Cold | Hot

Question 60

Where is temperature determined

Answer 60

In the brain

Question 61

What type of channels does thermoreceptors have

Answer 61

Transient receptor potential (a family of receptors)

Question 62

What type of channel is a transient receptors channel

Answer 62

Non specific cation channel

Question 63

What does a non-specific cation channel mean

Answer 63

They allow any cations in

Question 64

Name an example of a cold transient receptor potential channel

Answer 64

TRPM8

Question 65

Name an example of a warm transient receptor potential channel

Answer 65

TRPV3/4

Question 66

What type of fibres are cold receptors on

Answer 66

C and a delta fibres

Question 67

What type of fibres are warm receptors on

Answer 67

C fibres

Question 68

What is paradoxical cold perception

Answer 68

When cold receptors become excited by high temperature

Question 69

What does cutaneous nociceptors detect

Answer 69

Pain

Question 70

What is the structure of nociceptors

Answer 70

Bare nerve endings

Question 71

What is the threshold of nociceptors

Answer 71

High

Question 72

What are the 2 types of nociceptors

Answer 72

High threshold mechanoreceptors | Polymodal nociceptors

Question 73

What does high threshold mechanoreceptors detect

Answer 73

Localised pricking pain

Question 74

What fibres are the high threshold mechanoreceptors found at

Answer 74

A delta fibre

Question 75

What is the stimulus for polymodal nociceptors

Answer 75

``` Mechanical stimulus Damaging heat (above 46) Noxious chemicals ```

Question 76

What fibres are polymodal nociceptors found at

Answer 76

C fibres

Question 77

What does propioception detect

Answer 77

Mechanical status

Question 78

What are propioceptors

Answer 78

Sensory receptors from skeletal muscle

Question 79

What are the fibres/axons of prioceptors

Answer 79

Group 1 (axons from muscle) that are thickly myelinated

Question 80

What are the 2 propiceptors found in the body

Answer 80

Muscle spindles | Golgi tendon organ

Question 81

What does muscle spindles detect

Answer 81

Length and acceleration

Question 82

What type of fibres does muscle spindles contain

Answer 82

Intrafusal fibres

Question 83

What are the group of axons that muscle spindle fibres contain

Answer 83

Group 1a

Question 84

How does muscle spindle fibres become activated

Answer 84

When the fibres are stretched

Question 85

What does golgi tendon organ detect

Answer 85

Muscle tension

Question 86

What type of axons is golgi tendon organ innervated by

Answer 86

Group 1b afferents

Question 87

What are the 2 main ascending tracts

Answer 87

Dorsal column | Spinothalamic tract

Question 88

What fibres/axons does the dorsal column contain

Answer 88

A beta fibre

Question 89

What fibre/axon does the spinothalamic pathway contain

Answer 89

A delta and c fibres

Question 90

What type of sensory information does the dorsal column send to the Brian

Answer 90

Touch Vibration 2 point discrimination Propioception

Question 91

What type of information does the spinothalamic tract send to the brain

Answer 91

Pain | Temperature