Endogenous Control of Pain Flashcards
adequate stimulus for pain
anything causing tissue damage
peripheral receptors for pain
on free nerve endings-branch out and disperse
types of free nerve endings for pain
nociceptorsA-delta and C fiberssilentthermoreceptorsmechanoreceptors
A delta
small - light myelination
C fibers
small - no myelination
silent receptors
only with repeated pain stimuli-or inflammation
pain stimulates
attentionemotionANSmemory
pain
perception of noxious stimulus
nociceptive information
has multiple destinations(divergence)
spinothalamic tract
only conscious tract for pain
brainstem
spinoreticular and spinomesencephalic tract
hypothalamus
spinohypothalamic tract
limbic system
indirectly via RF and hypothalamus
spinothalamic tract
good localization-because its contralateral and has somatotopyeasier to test as clinician-because you are consciously aware
spinoreticular and spinomesencephalic tracts
bad localization-because bilateral pathwaysgood for attention, emotion, ANS, and memory
noxious stimuli
not emotionally neutral events
perception of pain
not an unchangeable property-can modulate
modulation of nociception
changes in nociceptors-change in dorsal horn-alter descending pathways
hyperalgesia
increased pain response to noxious stimulus-pain much more intense after secondary injury
allodynia
pain perception to normally not painful stimulus-ex/ sunburn
tissue injury
release of inflammatory mediators-decrease threshold of regular nociceptors-recruit silent nociceptors
axon reflex
pain stimuli come in-free nerve endings have trigger zone-great enough intensity, APs back out to free nerve endings-for further vasodilation and inflammation
modulation by descending pathways
input from hypothalamus, amygdala, cortex-to periaqueductal gray (midbrain)-synapse at nucleus raphe-magnus (caudal pons)-to dorsal horn
C fibers
absence of input from C fibers - tonic inhibition-from interneuronswith strong pain - C fibers stop inhibition pathway-allow stronger signal to go to brain
