NS 12 - Pain and nociception 2 Flashcards
what are the 2 types of 2nd order neurons that exist?
- nociceptive specific
- wide dynamic range
describe Nociceptive specific
inputs from nociceptors only
presence and location of noxious stimulus
describe wide dynamic neruons?
recieves input from nociceptors, mechanoreceptors and thermoreceptors
- respond a wide range of stimulus intensities
where the 2nd order neurones go next?
contralateral thalamus via the trigemino-thalamic tract to the ventrobasal nuclei or the posterior and medial nuclei
once passed the thalamus, where does it go then?
- primary somatosensory cortex
- insula
- cingulate gyrus - emotion
what is hyperalgesia?
increased pain from a stimulus that normally provokes pain
what is radiating pain?
pain appears to be spread beyond area affected
what is referred pain?
pain appears orignate from an area that is different to the injured area
describe referred pain
usually from a deep to superficial structure
- usually segmental : heart to left arm or maxillary sinus to teeth
what is the gate control theory?
an attempt to explain how pain signals may be modulated
what are the interneurones activated by?
segmental inputs and descending controls
when there is no input, why is the gate still closed?
the inhibitory neuron prevents the projection neuron from sending signals to the brain
normal somatosensory input happens when there is large fibre stimulation but the gate is still closed, why is that?
both the inhibitory neuron and the projection neuron are stimulated but the inhibitory neuron prevents the projection neuron from sending signals
nociceptive pain happens when there is small-fibre stimulation - the gate is now open, why?
small fibre stimulation inactivates the inhibitory neuron and the projector neuron sends signals to the brain informing it of pain and thus the gate is open
list the excitatory neurotransmitters
substance P
CGRP
glutamate
