Neuro - Nociception Flashcards
where are the somas of all somatosensory neurones located
dorsal root ganglia
where do the 2 branches of the soma depart to
one to the PNS
other to CNS
where do 1st order neurones enter
into the dorsal root and joins the dorsal column
what are examples of what 1st order neurones detect and where are they terminated
pain/temperature fibre
dorsal root
what are 1st order neurones classified as and why
pseudounipolar
2 axon branches
features of a Aβ neurone
touch
6-12micrometers
35-75m/s
features of Aδ
pain and temperature
free nerve endings
1-5 micrometer diameter
5-30m/s
features of C neurones
pain, temperature and itch
free nerve endings
0.2 - 1.5 micometer
0.5 - 2 m/s
what contains a complete representation of the somatic sensory periphery
thalamus
where is are 2nd order neurones terminated
thalamus
what does a painful heat cause (>43 degrees C)
TRPN1 channels open in C fibre endings
what mediates the affective-motivational aspect of the brain
multiple signals from the antolateral system to the reticular formation of the midbrain
features of Aβ - fast pain neurones
small and thinly myelinated
10% nociceptive fibres
sharp/quick pain
mechanical stimuli
afferent portion of the reflex arc
features of C fibres - slow pain
small and unmyelinated
90% of afferent sensory fibres
mechanical/thermal and chemical
potentially long term - aching, deep, visceral pain
what are the inflammatory mediators after tissue damage
prostaglandins
bradykinin
substance P
what do inflammatory mediators do
increase the sensitivity of nociceptors by reducing the threshold for depolarisation
what is the function of non-steroidal anti-inflammatory drugs (NSAID)
target the production of prostaglandins by inhibiting the enzyme COX
what is a feature of prostaglandins
they are vasodilators
inhibit aggregation of platelets
what is the substantia gelatinosa of the dorsal horn
gating mechanism in the spinal cord that can be open or closed in varying degrees
modulates incoming signals before they reach the brain
outline the descending control from the brains dorsolateral tract
stress
hypothalamus
periaqueductal grey
nuclease raphe
interneurons spinal cord
projection neurone
what is required to get to the periaqueductal grey from the hypothalamus
endorphines
what is needed to move from the periaqueductal grey to the nucleus raphe
enkaphilin
what is needed to reach the interneurons of the spinal cord from the nucleus raphe
seretonin
what is needed to move from the interneurones of the spinal cord to the projection neurone
enkaphilin
what is enkaphilin mediated inhibition
an endogenous opiod
what is the effect of enkaphilin mediated inhibition pre-synaptically
narrows the AP
limits neurotransmitter release
what is the effect of enkaphilin mediated inhibition post-synaptically
generates inhibitory potential
stops cell from reaching the threshold
