Pain

Question 1

What is the adaptive role of pain and what are it’s characteristics?

Answer 1

protective function
high threshold and limited duration

Question 2

What fibres mediate pain?

Answer 2

a-delta fibres and C fibres

Question 3

What type of pain are a-delta fibres associated with?

Answer 3

sharp stabbing pain

Question 4

What type of pain are C fibres associated with?

Answer 4

dull, aching pain

Question 5

What are characteristics of nociceptor endings?

Answer 5

free nerve endings
high threshold of activation

Question 6

What are polymodal responses in C fibres?

Answer 6

can respond to various types of pain - itching, mechanical, heat, and crude touch

Question 7

What stimuli do a-delta fibres respond to?

Answer 7

mechanical
heat
crude touch

Question 8

What kind of touch can pain receptors transmit?

Answer 8

crude touch
fine touch is for DCML

Question 9

Where do the axons cross over in the spinothalamic pathway?

Answer 9

antero-lateral funiculus

Question 10

In which pathway are the spinal lemniscus found?

Answer 10

spinothalamic pathway

Question 11

In the spinothalamic pathway, the ascending projection up to the thalamus is called?

Answer 11

spinothalamic tract

Question 12

Where do fibres terminate in the brain?

Answer 12

somatosensory cortex

Question 13

What are the attributes of pain?

Answer 13

• Location
• Pain quality – sharp stabbing, dull ache
• Pain intensity
• Frequency / duration
• Provoking / relieving events

Question 14

Why is the location of the pain important?

Answer 14

dermatomes can help locate damage to spinal regions or branches of trigeminal nerve

Question 15

What is referred pain?

Answer 15

These are perceived in one part of the body, but the pathology is elsewhere

Question 16

Where does referred pain come from?

Answer 16

Pain tends to refer from an internal organ to a superficial area e.g. skin

Referral due to a convergence of inputs in the CNS

Question 17

Where can pain from the heart be felt?

Answer 17

left shoulder, and forearm

Question 18

Where can pain from oesophagus be felt

Answer 18

left shoulder and forearm

Question 19

What does a mutation of SCN9A gene cause?

Answer 19

loss of NAV1.7 function
inability to experience pain
however sensory and motor tests normal

Question 20

What 7 factors can influence pain perception?

Answer 20

Genetic
Molecular
Cellular
Anatomical
Physiological
Psychological
Social

Question 21

What can rubbing the painful area activate?

Answer 21

a- beta fibres through mechanoreceptors (DCML)

Question 22

What does the bifurcation of the a-beta fibre activate?

Answer 22

activate inhibitory inter-neurones

Question 23

What do inhibitory inter-neurones inhibit?

Answer 23

2nd order projecting pain neurones

Question 24

What are the descending projections able to do?

Answer 24

inhibits projection neurones

Question 25

What composes the triple response to mechanical trauma?

Answer 25

wheal (swelling)
redness
flare

Question 26

What is an increased triple response disease called?

Answer 26

Dermatographia

Question 27

What mediators can release upon mechanical trauma?

Answer 27

potassium
prostaglandins
serotonin
bradykinin
platelets

Question 28

What does the release CGRP and substance P cause?

Answer 28

activation of mast cell to release histamine

Question 29

What does histamine do?

Answer 29

vasodilation, redness

Question 30

What does the release of bradykinin cause?

Answer 30

wheal (swelling)

Question 31

What does the dilation of blood vessels cause?

Answer 31

flare

Question 32

What are relieving factors for the triple response?

Answer 32

restrict blood supply via pressure, cold water
minimise effect of mast cell degranulation -antihistamine