Flashcards in MSK - PAIN PHYSIOLOGY Deck (37)
what is pain?
an unpleasant sensory and emotional experience assoc with actual tissue damage or described in terms of damage
processes involved in pain
translation of noxious stimulus into electrical activity at the peripheral nociceptor
propagation of pain signal as nerve impulses through the nervous system
modification/hindering of pain transmission in the NS eg by inhibitory neurotransmitters like endogenous steroids
conscious experience of pain
causes physiological and behavioural responses
what begins pain?
activation of nociceptors
what are nociceptors?
specific primary afferent neurones normally activated by intense noxious stimuli eg thermal, mechanical or chemical
how do nociceptors relay information to second order neurones?
chemical synaptic transmission
what are the neurotransmitters?
glutamate and peptides eg substance P and neurokinin A
how do second order neurones ascend the spinal cord?
the anterolateral system terminating in the thalamus
which tracts are involved?
what happens in the spinothalamic tract?
pain perception - location and intensity
what happens in the spinoreticular tract?
autonomic responses to pain, arousal, emotional responses, fear of pain
where does the sensory information go after the thalamus?
it is relayed by third order neurones to the primary sensory cortex
what are the types of nociceptors?
both types of nociceptors are myelinated. true/false
only adelta fibres are (thinly myelinated)
what do adelta fibres mediate?
first or fast pain eg lancinating, stabbing, pricking sensations
what do c fibres mediate?
second or slow pain eg burning, throbbing, aching sensations
what are the classifications of mechanisms of pain?
what is nociceptive pain and when is it provoked?
normal response to injury of tissues by damaging stimuli
only provoked by intense stimulation
what is special about nociceptive and inflammatory pain?
n- healing -> pain goes away)
I - promotes repair until healing occurs
what causes inflammatory pain?
activation of the immune system by tissue injury or infection
what activates the pain in inflammatory?
mediators released at the site of inflammation by leucocytes, vascular endothelium and tissue resident mast cells
what is hyperalgesia (caused by inflammatory pain)?
heightened pain sensitivity to noxious stimuli
what is allodynia (caused by inflammatory pain)?
pain sensitivity to innocuous stimuli
when is pain pathological?
when simple analgesics are no longer effective
what is pathological pain treated with?
antidepressants and anti epileptics
what are the two types of pathological pain?
dysfunctional and neuropathic