pain Flashcards
what is pain
a subjective unpleasant sensory or emotional experience associated with actual or potential tissue damage
what is subjective experience
fear, anxiety and panic -> motor actions, learned avoidance, behavior modification
what is nociception
event of sensing mechanical, chemical, and thermal stimuli, which have the ability or the potential ability to cause damge to the tissues
what is the difference between pain and nociception
pain requires awareness
what are nociceptors
free nerve endings of Adelta and C fibers
what do nociceptors encode for
physical insults into electrical signals and transduce them to the dorsal horn of the spinal cord
nociceptors can lower their activation threshold following repeated stimulation, which results in:
peripheral sensitization
how does pain travel
through 3 orders of neurons from the periphery to the brain cortex
describe the 3 orders of neurons for pain
- first order neuron - nociceptors -> spinal cord
- second order neuron - spinal cord -> thalamus
- third order neuron - thalamus -> somatosensory cortex
what are Adelta fibers
- fast conduction
- myelin
- sharp and pricking pain
what are C fibers
- slow conduction
- no myelin
- burning type pain
second order neurons
- low threshold mechanosensitive neuron (LT) - light touch, pressure, proprioception
- nociception specific neuron (NS) - noxious stimuli
- wide dynamic range neuron (WDRN) - wide range stimuli
neospinothalamic tract
fast transmission of pain and readily localized
paleospinothalamic tract
emotional and visceral response to pain
archispinothalamic tract
emotional and autonomic response to pain
third order neurons
relay information received from 2nd order neurons in the thalamus to the somatosensory cortex (awareness)
what is windup
progressive, frequency dependent facilitation of the responses of a neuron after the application of repetitive (usually electrical) stimuli
what horn is more esasily excitable after the application of a windup-evoking stimulus
dorsal horn
are windup and central sensitizations equivalent
no
can the presense or absense of windup by itself be a marker of the presence of central sensitization
no
what is central sensitization
a global event that involves all the pathways ascending and descending
windup is a phenomena limited to the:
spinal cord
what is hyperalgesia
increased response to a stimulus that is normally painful
what is allodynia
painful response to a normally nonpainful stimuli
why do we treat pain
- ethics
- decrease morbidity/mortality
- deleterious effects (cardiac output, cardiac work & oxygen ocnsumption, vasocontriction, immuno-suppression)
what are common signs of pain
thrashing, restlessness, vocalization, circling and continuous activity
dysphoria
- opioids, ketamine
- artic breeds, labrador ret
- emergence delirium, absent
pain
- response to manipulation
- aggression
- increase HR and BP
