Sensory Systems and the pathophysiology of pain

Question 1

nociceptors respond to

Answer 1

pain/ damaging stimulus

Question 2

two types of receptors

Answer 2

physiological (sensory)

pharmacological (protein)

Question 3

all sensory receptors TRANSDUCE their adequate stimulus into a depolarisation called the

Answer 3

receptor potential

Question 4

the size of the receptor potential encodes the

Answer 4

intensity of the stimulus

Question 5

receptor potential evokes what?

Answer 5

AP firing

Question 6

the frequency of AP firing also encodes for the

Answer 6

intensity of the stimulus

Question 7

receptive field encodes the

Answer 7

location of the stimulus

Question 8

APs are transmitted to the CNS via

Answer 8

axons

Question 9

cutaenous sensation is mediated by what 3 types of primary afferent fibres?

Answer 9

large myelinated

small myelinated

unmyelinated

Question 10

unmyelinated fibres detect

Answer 10

warmth and ‘slow’ pain

Question 11

small myelinated fibres detect

Answer 11

‘fast’ pain and pressure

Question 12

large myelinated fibres detect

Answer 12

touch, pressure and vibration

Question 13

the transmission of sensory information is via what three types of fibres?

Answer 13

mechanoreceptors

thermoreceptors

nocireceptors

Question 14

afferent neuron from pain and temperature (nocireceptive and thermoreceptive) travel up what?

Answer 14

the contralateral spinothalamic tract

Question 15

receptors for body movement, limb positions, fine touch discrimination and pressure (mechanoreceptors) all travel up via what?

Answer 15

dorsal column

Question 16

damage to dorsal columns causes loss of

Answer 16

touch

vibration

proprioception

(below lesion on ipsilateral side)

Question 17

damage to the anterolateral (contralateral spinothalamic) tract causes of loss

Answer 17

nociceptive and temperature sensation below lesion on contralateral side

Question 18

signal transduction in nociceptors is activated by

Answer 18

low pH

heat

local chemical mediators (bradykinin, histamine, prostaglandins)

Question 19

what is gate control theory?

Answer 19

non-painful input closes the nerves ‘gates’ to painful input, which prevents pain sensation from traveling to the CNS

Question 20

activity of Aalpha/beta fibres activates what in gate theory?

Answer 20

inhibitory interneurons

Question 21

inhibitory interneurons release opioid peptides (endorphins) that inhibit

Answer 21

transmitter release

‘closing the gate’

Question 22

local anaesthetics block Na+ and therefore

Answer 22

block APs and axonal transmission

Question 23

NSAIDs - basically block the production of

Answer 23

prostaglandins

so work well against pain associated with inflammation

Question 24

prostaglandins act on voltage gated sodium channels to allow for

Answer 24

depolarisation

and therefore AP firing

Question 25

opiates do what 2 things to stop pain

Answer 25

reduce sensitivity of nociceptors

block transmitter release in the dorsal horn

activate descending inhibitory pathways

Question 26

what is nociception?

Answer 26

the detection of tissue damage by A delta and C fibres

Question 27

C fibres are myelinated or unmyelinated?

Answer 27

unmyelinated

Question 28

Dorsal column carries what kind of signals?

Answer 28

Aalpha or Abeta axons

non-nociceptive mechanoreceptors

Question 29

the spinothalamic tract is the major ascending tract for

Answer 29

nociception

Question 30

what is central sensitisation?

Answer 30

the response of 2nd order neurons in the CNS to normal input both noxious and non-noxious

(noxious = painful/harmful)

Question 31

what is nociceptive pain?

Answer 31

a sensory experience that occurs when specific peripheral sensory neurons (nociceptors) respond to noxious stimuli

Question 32

what is neuropathic pain?

Answer 32

pain initiated or caused by a primary lesion or dysfunction in the somato-sensory system

Question 33

what are the 3 main components of central sensitization?

Answer 33

wind up

classical

long term potentiation

Question 34

wind up only takes place in

Answer 34

activated synapses

Question 35

classical involves the

Answer 35

opening up of new synapses

Question 36

long term potentiation involves mainly the

Answer 36

activated synapses (for intense stimuli)