BIOS1171 Lecture Notes - Lecture 6: Noxious Stimulus, Periaqueductal Gray, Vitreous Body
4 Sep 2018
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Detected by nociceptors which detect tissue destruction. Free nerve endings located under the skins surface (superficial to mechanoreceptors) Are polymodal respond to several forms of sensory stimulation. Fast nociceptors = a delta class fibre axons (myelinated axons) Slow nociceptors = c class fibre axons (unmyelinated) Where afferent nerve endings translate noxious stimuli into noxious impulses. Stimuli in response to heat, capsaicin: receptors respond to stimuli, exchange of sodium and potassium at cell membrane (depolarisation, action potential created and generated pain impulse. Pathways: - travels ipsilateral (dorsal column: discriminative peripheral nerve/trigeminal nerve > dorsal horn > anterolateral pathway > somatosensory cortex, affective-motivational peripheral nerve > anterolateral pathway > midline thalamic nuclei > anterior cingulate cortex. Necessary to escape from danger or to continue important activity. Pain controlled through the spinal and descending pathways. Done through inhibiting nociceptive neurons by producing activity in low threshold mechanoreceptors (eg. acupuncture, tens) Tens: transcutaneous electrical stimulation (electrodes on the skin)
