Somatic senses, motor control

Question 1

type of cell, location: nociceptors

Answer 1

for pain,
located at dermal/epidermal juction
- free nerve ending

Question 2

type of cell, location: thermoreceptor

Answer 2

for absence/presence of heat
- free nerve ending

cold: epidermis
hot: in dermis

Question 3

type of cell, location: hair root plexus

Answer 3

• free nerve ending, dermis
• around hair root
• touch sensation

Question 4

type of cell, location: Merkel nerve ending

Answer 4

• free nerve ending
• mechanoreceptor (touch)
• epidermal/dermal junction

Question 5

define nociception:

Answer 5

unpleasant sensation arising from noxious (unwanted) stimuli

Question 6

types of nociceptors:

Answer 6

• mechanical
• thermo-mechanical
• polymodal (chemical, mechanical and thermal)

Question 7

‘fast’ pain: type of pain, eg

Answer 7

A fibres

- acute, sharp pain

Question 8

‘slow’ pain: type of pain, eg

Answer 8

C fibres

- burning, aching, throbbing pain

Question 9

define thermoception:

Answer 9

sense of presence or absence of heat

Question 10

list thermoreceptor types:

Answer 10

cold and warm

Question 11

cold receptor features:

Answer 11

10-40˚C

• epidermis
• A fibres

Question 12

warm receptor features:

Answer 12

32-48˚C

• dermis
• C fibres

Question 13

type of cell, location: Meissner corpuscle

Answer 13

aka. tactile
- encapsulated cell
- for touch
- dermal/epidermal junction

Question 14

type of cell, location: Ruffini corpuscle

Answer 14

aka bulbous

• encapsulated cell
• mechanoreceptor
• dermis

Question 15

type of cell, location: Pacinian corpuscle

Answer 15

aka lamellar

• encapsulated cell
• mechanoreceptor
• deep dermis

Question 16

define tactition:

Answer 16

sense of touch, pressure, vibration, tickle, itch

Question 17

superficial mechanoreceptors:

Answer 17

• Meissner’s tactile corpuscle (fine touch)

- Merkel nerve endings (touch)

Question 18

subcutaneous mechanoreceptors:

Answer 18

• Pacinian (lamellar) corpuscles (deep pressure)
• Ruffini (bulbous) corpuscles (stretch due to movement)
• hair root plexuses (movement of hair)

Question 19

define proprioception:

Answer 19

• sense of movement, joint position sense, the sense of object’s weight

Question 20

proprioceptors:

Answer 20

• muscle spindles
• Golgi tendon organs
• joint kinaesthetic receptors

Question 21

muscle spindles: location

Answer 21

intrafusal muscle fibres:
- embedded inside skeletal m.

extrafusal muscle fibres: skeletal muscle

Question 22

stimulus for muscle spindle:

Answer 22

muscle stretch (lengthening)

Question 23

muscle spindles: fibre group

Answer 23

Type Aå

Type Bß

Question 24

distribution: muscle spindles

Answer 24

skeletal muscles

Question 25

how does stretch reflex work: general

Answer 25

stretch reflex causes contraction of muscle that has been stretched

Question 26

morphology: Golgi tendon organs

Answer 26

• thin capsule of ct. over few tendon fascicles/ collagen fibres
• surrounded sensory nerve endings

Question 27

stimulus: Golgi tendon organs

Answer 27

• tension

Question 28

Golgi tendon organs: fibre group

Answer 28

Type Aå

Question 29

Golgi tendon organs: location

Answer 29

musculotendinous junction of skeletal muscle

Question 30

how does tendon reflex work: general

Answer 30

causes relaxation of muscle attached to stimulated tendon organ

Question 31

3 main somatosensory pathways:

Answer 31

• dorsal column
• anterolateral system
• spinocerebellar pathways

Question 32

1st order sensory neurons:

Answer 32

• from sensory receptor to spinal cord/ brainstem
• travel in peripheral nerves
• cell body located in dorsal root ganglion

Question 33

2nd order sensory neurons:

Answer 33

• spinal cord to thalamus
• travel in spinal cord tracts
• decussate (cross over in ‘x’) in spinal cord/ brainstem

Question 34

3rd order sensory neurons:

Answer 34

• thalamus to primary somatosensory cortex

- travel in internal capsule

Question 35

dorsal column conveys:

Answer 35

• fine touch
• pressure
• vibration
• conscious proprioception

Question 36

anterolateral system conveys:

Answer 36

• pain
• temperature
• itch
• tickle