Quiz 1 Flashcards
AB fibres
found in muscle spindle, 100m/s.
A-delta fibres
well localised, first pain, 40m/sec, Sharp, pricking pain
Type 1 pain
Pain from chemical or mechanical stimuli
Type 2 pain
Pain to thermal stimuli
C fibres
Slow second pain, 1-2m/s, dull burning quality
TRPV1 channels
Heat and chemical (approx 43 deg), capascin an acid sensiing (H+) V1 cars= hot
TRPM8
cold (+0), both noxious and innocuous, menthol M8 its cold
TRPA1
cold (-0deg)ad GI tract smooth muscle A for anus
ASIC 1
Git smooth muscle, cmustard, garlic, smoke
ASIC 2/3
cardiac and skeletal muscle, can be activated by anaerobic metabolism ASCIS is a sport shoe
naV channels
influence flow of sodium and therefore influence resting membrane potentials and thresholds.
NaV 1.7- in sympatetic and C fibres, upregulated in inflammatory conditions
Nav 1.8- c fibres, action potential in cold conditions
Nerve growth factor
released by macrohages and t lymphocytes
Tyrosine kinase is reeptor
1. binds directly to nociceptors
2. activates mast cells- degranulate- release histamie
3. increase sympathetic sprouting of nerves- increased receptive field
Interneurons
Excitatory glutamergic or inhibitory GABA/ glycine
Effects of intracellular Ca2+ on CS
- Increased Ca2+- activation of kinases- phosphorylate NMDA and AMPA- increased channel open times, quikcer Mg2+ remova, inreaed sensitivity
- Ca2+ activates Calmodulin (CaMK)- phosphorylates AMPA and makes modified AMPA receptors that are more efficient and open at loer activation levels
- PKC activation reduces effects of GABA and glycine and descending inhibition from PAG
Astrocytes
homestasis, neurotransmitter release and uptake, release NO, PGE2 and glutamate in inflammatory conditions
Microglia
like macrophages, accumulate in dorsal horn at injured nerve, neurotransmitter/cytokine release, activate in nerve injury, release SP, ATP, glutamate
Spinomesencephallic tract
travels to PAG, parabrachial, amydala. Involve in emotional response to pain
Spinoreticular tract
travels to hypothalmus, ANS, involved in stress and motivaional affective and autonomic centres of pain
Thalamus
involved in the sensory discriminative and motivational affective part of pain
Lateral nociceptive thalamus
contains 2 nucle VPL: nociception from body VPM: nociception from face sends info to s1 and S2 Nuclei have lower thresholds during inflammation
Medial nociceptive thalamus
Recieve input frm SMT and SRT, responds to nociception from all parts of body, wide receptive field, play a role in intensity
Project to limbic system, motivational affective part of the thalamus
Lateral pain system
refers to the sensory discrimintaroy aspet of pain from s1 and s: localisation, intensity and quality
S1 vs S2
S1: localisation and intensity of pain
s2: bilateral receptive fields, vague localisation, projections to limbic system therfore emotional
Medial pain system
refers to everything other than S1 and S2
PAG, amygdala, cingulate cortices, insular cortices
affective and emotional aspects of pain
ACC
connected to thalamus, involved in attention and escape from pain and emotion
Insula cortex
awarenss and withdrawal from pain
Amydala
puts emotions and meaning onto everythig, behavioural adaptations, also has inputs from SMT
Lateral nucleus
(In amygdala) recieves affective, cognitive and sensory informatoion from thalamus, somatosensory and limbic reas.`
Central nucelus
recieves processed info from lateral nucleus.
recives info about anixiety and fear
recieves raw information from spinal cord via parabrachial nucleus (pons)
also connectedto PAG, dorsal reticular nucleus, substantia nigra, locus coeruleus and raphe nucleus
Rostro-ventral medulla
includes nucleus raphe magnus and reticular formation. inhibitory and excitatory function. Shifts ON cells ON.
ON cells
produce facilitatory impulse that increases glutamate and substance P
PAG-RVm axis
PAG releases opiods– RVM releases serotonin– serotonin stops transmission of nociceptor signal at dorsal horn, namely c fibre
PAG RVM axis influenes
influenced by cognition (ACC), emotion (M/ACC), stress (hypothalamus) and fear (amygdala)
Diffuse noxious inhibitory control
phenomenon whereby pain in one body region can inhibit pain in another body region
COnditioned pain modulation
tests for diffuse noxious inhibitory control as there is said to be a loss of this in chronic pain. Conditioned stimulus of cold water and test stimulus of thermal/ mechanical pressure. in chronic pain there will be absent or increased sensitity to test stimulus
Stress and pain ST
ST: Adrenal glands release cortisol- macrophage and SNS activity increased and decreased threshold for inflammatory response-_ macrophages active microglia
stress and pain LT
chronic release of cortisol= chronic inflammatory response= cytokines producing systemic response = affecting serotonin, adrenaline, opiods
Development of widespread pain
due to increase in receptive fields and referred pain. and opening of inactive/ adjacent synapses in DH.
features of CS pain
pain is widespread, allodynia, spontaneous, hyperalgesia, chnages in mood, unrefreshed sleep, poor concentration, fatigue
Spinomesencephalic tract and supraspinal descending modulation
SMT arises as 2nd order neuron > decussate to anterolateral system > ascend up spinal cord in white matter > terminate at PAG > synapse with descending neuron > descend down MB, decussate at pons > continue down spinal cord in lissaurs tract > terminate at lamina 2 > release Ca > inhibit SP and G from 1 order neuron > decrease pain transmission.
