BMS11004 WEEK 11 - TUESDAY Flashcards
pain, nociceptors, afferent fibres, tracts
define specificity theory
pain is a distinct sensation, detected/transmitted by specific receptors to distinct brain area
define convergence theory
pain is integrated, plastic state represented by pattern of convergent somatosensory activity within distributed network (neuromatrix)
what type of fibre (a, b, y) are lightly myelinated nociceptors, what modality are they, how fast
Aδ (alpha delta)
fast (20m/s)
mechanosensitive, mechanothermal-sensitive
what type of fibre (a, b, y) are unmyelinated nociceptors, what modality are they, how fast
C fibre
slow (2m/s)
polymodal= mechanical, thermal, chemical
when are nociceptors most easily demonstrated
in heat response- find afferent whose activity correlate with pain perception
what fibre types mediates fast pain
sharp, immediate
mimicked by direct stimulation of Aδ (delta) fibre nociceptors
what fibre types mediates slow pain
diffuse, delayed, long-lasting
mimicked by stimulating C fibre nociceptors
when you cut yourself, what nociceptors activate
first sharp pain = Aδ
replaced by long dull pain = C fibres
what are molecular pain receptors
specific molecular receptors associated with nociceptive nerve endings and activated by heat, hot chillis
capsaicin receptor (TRPV1) is a specific molecular receptor. describe what fibres it is activated in, how
activated in nociceptive Aδ and C fibres at 45c by capsaicin (vanilloid, active component in chilli)
name the 2 ways that molecular receptors can respond in pain
responds to heat directly and fire
capaicin can bind and cause it to fibre
name the 2 components of central pain pathways
sensory discriminative - signals location, intensity, stimulus type (involve spinothalamic tract)
affective motivational- signal unpleasant, enables fight/flight autonomic response
what is spinothalamic tract also known as
anterolateral system
explain topological maps of pain
topologically represented in cortex, region responding to painful stimulus and response correlates to pain intensities
explain what brain areas are linked to affective-motivational response to pain
insula, cingulate cortex (limbic system)