nociception Flashcards
unpleasant sensory and emotional experience associated with potential tissue damage
pain
transduction process of pain
nociception
specialized bare nerve endings
nociceptors
3 classes of nociceptors
high threshold mechanical, thermal or polymodal
nociceptors which respond directly to noxious tactile stimulo, mediate sharp pricking pain; thinly myelinated
high threshold mechanical
nociceptors which sense noxious temp. changes
thermal
nociceptors which respond indirectly to injury by means of chemicals released from traumatized tissue; slow burning pain
polymodal
mechanical receptors are also activated by painful stimulus; carried by what type of fibers (not actually pain just a warning)
A alpha and A beta
fast pain uses what fibers and feels like?
a delta fibers and sharp, pricking pain
slow (chronic) pain uses what fibers and feels like
C fibers (polymodal receptors); burning, throbbing and aching
channels which respond to noxious heat or chemicals
TRP- channel
channels which respond to noxious cold
TRPA1
channel which responds to mechanical and some chem. stimuli
epithelium Na channel
receptors which respond to P2X (purines, usually ATP)
purinergic receptor
The TRP channels are permeable to what ions and are polymodal
Ca/Na
the TRP are activated by ____ and ____; temp. above 45
vanilloids (pepper) and protons
the thermo-TRPs channels are all ____ sensitive and have different ranges and thresholds
temp.
The ENaC channel is acid sensitive and gated by ___
protons
the P2X receptors are ___ gated and have binding site at N-terminus and in lysines
ATP
____ nociceptors are regulated by their environment (tissue damage results in inflammation)
polymodal
increased response to a painful stimulus
hyperalgesia
stimulus that was not painful before injury but now is
allodynia
primary hyperlagesia
pain confined to a region of skin that was intially damaged
secondary hyperalgesia
site becomes hypersensitive to stimuli, increased pain sens. of region surrounding
nociceptors can react with any number of cells such as
injured epithelial, immune cells, neuropeptides, mast cells, glial cells
many of the peripheral mechanisms for inducing primary hyperalgesia ___ regulate pain receptors
indirectly
pain receptors activated in primary hyperalgesia
bradykinin and NGF
nociception signaling (1°): the bradykinin receptor is released by macrophages and mast cells and activates G-protein which acrivates
phospholipase C, PIP2, IP3 and DAG; calcium is released and it activates protein kinase C —> depolarizes cell
nociception signaling (1°): protoglandins E2 binds to its receptor and binds to Gs which activates
adenyl cyclase and cAMP –> protein kinase a —> TTX resistant Na channel (blocks poisons) Na rushes in
nociception signaling (1°): ATP binds to P2X and increases what ion release
Na+ and Ca2+ or second messenger GPCR
nociception signaling (1°) : ADP binds to ___
P2Y
nociception signaling (1°) : adenosine binds to ___ ___
adenosine receptors
produce mediators that sensitize nociceptors
immune cells
2 mechanisms by which secondary hyperalgesia occurs (in spinal cord)
- increase activation of astrocytes
- activates of NMDA glutamate receptor
NMDA glutamate actiavtes has both short term and long term effect on pain neurons in
spinal cord
Wide dynamic range neurons recieve innervation from both ___ and ___ sensory neurons
pain and mechanoreceptive
the WDR neurons are excited by C fibers but inhibited by ___
mechanoreceptive fibers
the WDR neurons are responsive to what somatosensory modalities
thermal, chemical, mechanical
the first central mechanism activates astrocytes and infiltration of ____ cells to secrete cytokines and growth factors
immune
DRG afferents (a delta and C) send axons into ___ spinal cord
dorsal
a delta fibers make synapses in dorsal horn and _____ in spinal cord
decussate
C fibers in spinal cord ___ and move up and down spinal cord
bifurcate (lissauers tract)
a delta fibers move in rexeds laminae __ and __
I and V
C fibers move in rexeds laminae __ and __
I and II
tract which mediates sensory discriminative information (location, quality and location)
spinothalamic tract
second order neurons in spinothalamic tract project to ___ of thalamus
VPL
nociception remains seperate from mechano and proprioceptive info up to __
S1
affective motivation (second pain) pathway in anterolateral conveys motivation aspects such as
fear, anxiety, autonomic activation
