NB12 Noiception Flashcards
What are the 2 types of pain fibres?
A-delta and C-fibres
Give the following for a) A-delta and b)C-fibres
1) size
2) myelination
3) conduction speed
4) pain type
5) respond to..
a) 1) 1-5 micrometers b)1) 2.5
2) a) yes ,thin b) no
3) 20m/s b) 2m/s (not myelinated)
4) a) sharp,fast b) dull, slow ache
5) a) mechanical stimuli ( pin prick), hot cold
b) multimodal lots
Which laminae in the dorsal horn do C fibres synapse in?
What does these feed into to reach anterolateral pathway?
1 and 2 which feed to 4 and 6 ( interneurons) then these decussate
then to anterolateral pathway to thalamus
Which laminae in the dorsal horn do A-delta fibres synapse in?
What does these feed into to reach anterolateral pathway?
1 and 5 which feed to second order neurones which decussate then to anterolateral pathway to thalamus
What 2 things can cause peripheral sensitisation?
What releases the chemicals that causes sensitisation?
e.g. of chemicals
What is sensitised?
1) damdge- direction action=chemical release
2) Inflammation- immune cells (neutrophils)
e.g. histamine, ATP
nociceptors are sensitised
What occurs in central sensitisation?
receptors AMPA and NMDA involved
some kinases
then effects transcription factor resulting in more activity
Where does central sensitisation occur?
spinal cord (laminae 1 and 5)
thalamus
amygdala
anterior cingulate cortex
1) In TM disorders what can increase general pain sensitivity?
2) Does in occur on one or both sides?
3) Does it occur at the TMJ?
4) What do we know about the pathophysiology?
1) contraction of orofacial muscles
2) yep both sides, bilateral pain sensitivity
3) yep and elsewhere (reffered pain likely (head, neck, ear)
4) multifactorial- not fully understood
In the gated-theory of pain how does A-alpha and A-beta neurons reducing our feeling of pain?
they synapse in laminae 3 , from there inhibitory interneurons travel to laminae 1 and 3 causing IPSE
What areas are involved in pain perception?
1) primary somatosensory cotex: localisation , type
2) hypothalamus and limbic system: emotional response
3) thalamus and pain perception: decides where it gets sent ventral posteromedial and ventral posterolateral
1)Why do we experience refereed pain?
due to convergence of sensory input e.g viscera of heart and skin
How is the raphe nucleus innervated?
sensory cotex/frontal/limbic system
periventricular nucleus of hypothalamus to synapse in
periaqueductal gray of midbrain exiting neurons synapse in..
raphe nucleus in medulla
What is the effect of raphe spinal on the gated theory of pain?
activates laminae 2, inhibitory interneurons to laminae 1 and 3 reducing activation of anterolateral system
name 3 opoids
where are they present?
eukephalin, endorphin and dynorphin
periventricular nucleus of hypothalamus
What opoids are used after surgery?
morphine
