physiology and pathophysiology of pain Flashcards Preview

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Flashcards in physiology and pathophysiology of pain Deck (48):
1

what part of the brain does pain get transmitted to?

thalamus

2

what is nociception?

the detection of tissue damage by specialized transducers connected to A-delta and C fibres

3

what are nociceptors?

free nerve ending of A delta and C fibres

4

what do nociceptors respond to?

thermal,chemical, mechanical noxious stimuli

5

where do nociceptors synapse?

spinal cord

6

what type of pain are A delta fibres responsible for?

sharp or "first" pain

7

what type of pain are C fibres responsible for?

dull pain which comes after the initial sharp pain

8

what are the 3 types of neurons that are predominantly found in grey matter?

low threshold mechanoreceptive neurons
nociceptive specific neurons
wide dynamic range neurons

9

where do the spinothalamic tracts relay information to in the brain?

thalamus

10

what rexed areas does the spinothalamic tract arise from?

2 and 5

11

where does the LATERAL STT terminate?

ventroposterior thalamic nuclei

12

where do the ventroposterior thalamic nuclei feed to?

somatosensory cortex

13

where does the VENTRAL STT terminate?

medial thalamic nuclei

14

where do the medial thalamic nuclei project to?

limbic system
anterior cingulate cortex
insular cortex

15

where does pain perception occur?

somatosensory cortex

16

what is the lateral part of the pain matrix composed of?

somatosensory cortex
ventroposterior thalamic nuclei

17

what is the medial part of the pain matrix composed of?

amygdala
hippocampus
cingulate and prefrontal cortexes
insula
brainstem centres

18

what is the lateral part of the pain matrix involved in?

sensory discriminative part of nociception

19

what is the medial part of the pain matrix involved in?

affective and emotional components as well as descending control of pain

20

where are descending pathways located?

from the brain to the dorsal horn

21

what is the usual effect of descending pathways?

usually decrease pain signal

22

what kind of system are descending pathways?

noradrenergic system

23

what is hyperalgesia?

leftward shift of the stimulus response curve; increased perception of pain or perception of non noxious stimuli as noxious

24

when does hyperalgesia occur?

whenever there is tissue damage and inflammation?

25

what is primary hyperalgesia?

hyperalgesia at the site of injury

26

what is secondary hyperalgesia?

hyperalgesia in tissue surrounding the injury

27

what is allodynia?

dynamic mechanical hyperalgesia brought on by light touch

28

what changes occur in nociceptors in hyperalgesia?

exaggerated response to normal and supranormal stimuli

29

what is central sensitization?

response of second order neurons in the CNS to normal input which can be both noxious or non noxious

30

what are the 3 components of central sensitization?

wind up
classical
long term potentiation

31

what kind of synapses does the wind up phase of central sensitization involve?

only activated synapses

32

what effect does the wind up phase have on the neurons it affects?

progressively increases the response of the neurons

33

when does the wind up phase manifest?

only over the course of a stimulus and ends with the stimulus

34

what does the classic phase of central sens. involve?

opening of new synapses - new synapses start to receive input and record nociception

35

what is the wind up mechanism chemically mediated by?

substance P and CGRP

36

what receptor when activated by glutamate can trigger classical central sensitization?

NMDA

37

what is the clinical reuslt of classical central sensitization?

secondary hyperalgesia

38

how can classical central sens. be maintained after it has been activated?

low intensity of the offending stimuli

39

what are 2 types of central sensitization?

segmental
suprasegmental

40

what is nociceptive pain?

pain that occurs when specific peripheral sensory neurones respond to noxious stimuli

41

what are some features of nociceptive pain?

pain typically localised at site of injury
usually time limited and resolves when damaged tissue heals
tends to respond to conventional analgesics

42

what is neuropathic pain?

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

43

what are some features of neuropathic pain?

painful region occurs in the neurological territory of the affected structure of the brain
almost always chronic
responds poorly to conventional anaesthetics

44

what are some methods to stop pain transduction?

NSAIDs
Ice
rest

45

what are some methods to stop pain transmission

opioids
anticonvulsants
DREZ
cordotomy

46

what are some ways to stop pain perception?

distraction
relaxation
mirror box therapy
cognitive behavioural therapy

47

does chronic pain serve a protective function?

no

48

what are some ways to stop descending modulation of pain?

opioids
antidepressants
spinal cord stimulation