pain mechanism and management Flashcards
nociception
perception of injurious stimuli
factors influencing pain perception
cognition
mood
context
genetics
chemical+structural
injury
types of pain
nociceptive
neuropathic
acute
chronic
neuropathic pain
chronic maladaptive pain after TBI
how long does chronic pain last
3 months+
which type of pain is often resistant to analgesics
neuropathic
how is pain intensity conveyed by nocioceptors
frequency coding - freq of discharge
what factors increase speed of transmission along an axon
increased axon diameter
myelination
which axons convey pain
A delta
C
what do A delta fibres convey
pain
temperature
what do C fibres convey
pain
temperature
itch
chemoreception
which fibres convey first pain and second pain
first - A delta
second - C
what do TRP and TRPM8 channels on thermal nociceptors transduce
TRP - heat
TRPM8 - cold
what do thermal nociceptors respond to
heat and cold
what do mechanical nociceptors respond to
excess pressure
mechanical deformation
what do chemical nociceptors respond to
inflammatory mediators
inflammatory mediators
histamine
prostaglandins
proteases
bradykinins
serotonin
ATP
H+
potassium
what type of receptor are most nociceptors
polymodal - respond to temp+pressure+mechanical deformation+inflammatory mediators
how does capsaicin prevent response from nociceptors
overstimulates receptor
what does substance P do
attracts histamine releasing cells
dilates blood vessels
alters cell signalling pathways to modulate pain perception
erythromelalgia
neuropathy characterised by recurrent burning pain, warmth, and redness of extremities
what causes primary erythromelalgia
Autosomal dominant genetic mutation causing hypersensitive nav1.7 channel
what part of the brain does the spinothalamic tract transmit to
thalamus
where does the spinothalamic pathway decussate
second neurone in spinal cord immediately after synapse with primary afferent
where does the DCML pathway decussate
second neurone at medial lemniscus of medulla
which part of the cortex controls the sensory-discriminative aspect of pain
somatosensory cortex
which part of the cortex controls the affective-motivational aspect of pain
anterior cingulate cortex and insular cortex
discriminative pain pathways
spinothalamic tract
trigemino-thalamic tract
phantom pain
feeling pain where a missing body part should be
what causes phantom pain
mal-adaptive plasticity
what causes referred pain
primary afferent from skin and primary afferent from viscera converge on same secondary neurone
why does rubbing an injury reduce pain
Melzack and Walls gate theory of pain - free nerve endings in the deeper layers of the skin respond to touch by inhibiting spinal transmission of pain signals from the body to the brain
areas of the brain involved in descending pain modulation
Anterior cingulate cortex
hypothalamus
nucleis cuniformis
periaqueductal grey
Dorsolateral pontine tegmentum
rostral ventromedial medulla
where are cannabinoid receptors present
pain pathways at peripheral and central levels
CNS
GI
Bones
Immune system
Muscles
where are endocannabinoids synthesised
membranes of neurones and other nervous cells
cannabinoid receptors
CB1 CB2
do cannabinoids increase or decrease NT release
decrease
release of which NTs are inhibited by activation of cannabinoid receptors
L-glutamate
GABA
noradrenaline
dopamine
serotonin
ACh
CNS structures activated by nociceptive stimuli
spinal cord
thalamus
somatosensory cortex
anterior cingulate cortex
insula
amygdala
prefrontal cortex
hippocampus
