PHY2011 Lecture Notes - Lecture 19: Trpm8, Trpv, Channel I
20 Jun 2018
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Week 7 L2 (T4L6) -somatic sensation 2 -non-discriminative
Temperature (within normal ranges)
oBeyond normal ranges, it has to do with pain (nociceptors)
Thermoreceptors:
oNerve endings of Aδ and C nerve fibres
oNo extra accessory structures
oNeurons have large RF -don’t need to modify stimulus
oTemp sensations not localised/discriminatory
oLocalisation of hot/cold objects is due to cutaneous touch receptors
o Different ion channels, but from the same family
TRPV ion channels
4 subunuits – symmetrically arranged around ion pore
Change in temp conformational change, influx of NA+ & Ca2+,
depolarisation APs
oCold detection: TRPM8
oHot detection: TRPV1-4
Pain
oFree nerve endings (Aδ and C nerve fibres)
oNo modification needed no accessory structures
oLocated at dermis, just below skin surface
oAδ nerve fibres
High threshold mechanoreceptors
Thermoreceptors
oC nerve fibres
Polymodal -detect all types
oTRPV1 channel
I
oNociceptors are selective for temperatures that are damaging (extremely hot or
cold)
Three features of pain perception:
oFast & slow pain
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Document Summary
Week 7 l2 (t4l6) -somatic sensation 2 -non-discriminative. Temperature (within normal ranges: beyond normal ranges, it has to do with pain (nociceptors) 4 subunuits symmetrically arranged around ion pore. Change in temp conformational change, influx of na+ & ca2+, depolarisation aps: cold detection: trpm8, hot detection: trpv1-4. Pain: free nerve endings (a and c nerve fibres, no modification needed no accessory structures, located at dermis, just below skin surface, a nerve fibres. I: nociceptors are selective for temperatures that are damaging (extremely hot or cold) Three features of pain perception: fast & slow pain. Fast sharp pain, followed by slow dull pain. Due to a (fast) and c (slow) nerve fibres: referred pain. Two nerve fibres send information to the same place. Ie skin pain and heart pain: pain sensitisation. Allodynia: things that were not painful become painful where injury has occurred.
