pain: acute and chronic Flashcards
definition of pain
unpleasant sensory and emotional experience associated with actual or potentially tissue damaged
acute pain
sudden onset and usually result of a clearly defined cause i.e. injury
nociceptive pain
pain that arises from actual or threatened damage to non neural tissue and is due to activation of noicieptors
chronic pain
pain lasting more than 12 weeks
nociceptive stimulus
an actual or potential tissue damaging event transduced and encoded by noicieptors
nociceptor
a high threshold sensory receptor of the peripheral somatosensory NS that is capable of transfusing or edging noixious stimuli
noxious stimuli
stimulus that is damaging or threatens damage to normal tissue
types of chronic pain
inflammatory pain
neuropahtic pain
what is inflammatory pain
associated with tissue damage and resulting inflammatory process
what is neuropathic pain
pain caused by a lesion or disease of the somatosensory NS
what is sensitisation
increased responsiveness of noiceptive neurones to their normal input
what is hyperalgesia
increased pain from stimulus the normally provokes pain
allodynia
pain due to a stimulus that does not usually cause pain
what do neuropeptides do
act as neurotransmitters and lead to increased inflammation
peripheral sensitisation
increased responsiveness/reduced threshold of noicpeptive neuroens in the PNS
central sensitisation
increased responsiveness of noiceptive neurones in the CNS to normal afferent input
peripheral elements of chronic pain
primary afferent nerve fibres
sensory nerve fibres
central elements of pain
terminal of sensory fibre in dorsal horn
neural transmission across to dental neurone
nociceptors in peripheral nerves
A delta C fibres (peptinergic/non peptidergic)§
what channels will there be at nerve terminals for noicpetors
TRP channels
others
explain transmission in the dorsal horn
glutamate released from afferent fibres
activates AMPA
this leads to a reposnce in the dorsal horn neurones
what contributes to the sensitivity of the noicpetors
inflammatory soup
explain contribution of glial cells in central sensiisation
activation of microgila and astrocytes cause release of cytokines
increase AMPA and NMDA receptor activity, increase I neuronal excitability
explain central sensitisation
(increase in synaptic efficacy between terminal and dorsal horn)
prolonged activity of noicpeptors = release glutamate
AMPA and NMDA remove mg block
increases Ca into pre
increased excitability of post cell
