Peripheral Sensory Mechanisms

Question 1

Skin mechanorecepetors

Answer 1

merkel, meissner, ruffini pacinian

Question 2

Meissner corpuscles are located

Answer 2

close to the surfaceof the skin in crests of dermis

Question 3

Merkel complexes are located

Answer 3

close to the surface of the skin in epidermal valleys

Question 4

Ruffini organs are located

Answer 4

deeper in the skin within the upper dermis

Question 5

Pacinian corpuscles are located

Answer 5

deeper in the skin within the lower dermis or subcutaneous layer

Question 6

Pacinian corpuscles respond to

Answer 6

vibration (transient response)

Question 7

How do Pacinian corpuscles transduce vibration?

Answer 7

vibration stretches the membrane in which ion channels lie, pulling them open allowing Na+ to rush in

Question 8

Slowly adapting receptors

Answer 8

show initial response to a stimulus, then encode the stimulus as time goes on until it goes away - continual information about how much stimulus is still being applied

Question 9

Rapidly adapting receptors

Answer 9

only care about changes - when the stimulus comes on and when it is removed

Question 10

Which mechanoreceptors are slowly adapting?

Answer 10

Merkel and Ruffini

Question 11

Which mechanoreceptors are rapidly adapting?

Answer 11

Meissner and Pacinian

Question 12

Merkel complexes respond to

Answer 12

pressure/indentation (sustained response)

Question 13

Ruffini organs respond to

Answer 13

skin movement and stretch (sustained response)

Question 14

Meissner corpuscles respond to

Answer 14

skin movement (transient response)

Question 15

Tactile receptors respond to

Answer 15

only gentle forces on the skin eg touching a blunt object; tell us about external environment

Question 16

Nociceptors respond to

Answer 16

more intense stimuli/tissue damage eg increasing temperature causing change to the tissue that releases mediators; tell us about internal environment

Question 17

Mechanoreceptors conduct at a velocity of

Answer 17

~50m/s

Question 18

Why do dermatome regions differ from peripheral nerve innervation patterns?

Answer 18

formation of plexuses and branching/crossing over of nerve roots leads to different regions of innervation by peripheral nerves than their cervical roots

Question 19

Damage to a peripheral nerve shows what pattern of peripheral sensory loss?

Answer 19

peripheral nerve innervation (eg ulnar, radial on dorsum of hand), not dermatomal (eg C6, C7, C8 on dorsum of hand)

Question 20

Damage to a cervical nerve root will show what peripheral pattern of sensory loss?

Answer 20

Dermatomal ie C6-C8 distribution on the dorsum of the hand

Question 21

Cell bodies of mechanosensory afferents are in

Answer 21

DRG for 31 spinal nerves, trigeminal ganglia for trigeminal nerves

Question 22

Cell bodies of nociceptor afferents are in

Answer 22

DRG

Question 23

What happens to pain and temperature fibres at the spinal cord?

Answer 23

They synapse and cross over to ascend on the contralateral side of the spinal cord; this is opposite to mechanosensory afferent fibres

Question 24

Mechanosensory afferent fibres ascend on which side of the spinal cord?

Answer 24

Ipsilateral

Question 25

Pain and temperature afferents ascend on which side of the spinal cord?

Answer 25

Contralateral (synapse first in SC)

Question 26

Pain and temperature receptor response is disrupted by

Answer 26

Spinal cord level lesions on the contralateral side

Question 27

Touch receptor response is disrupted by

Answer 27

Spinal cord level lesions on the ipsilateral side