modality : class of stimulus on skin
location : set of sensory receptors
intensity : the response amplitude of each receptor
timing : how quickly the energy is received or lost by the receptor
submodality : respond to a limited rage of stimulus eneries. - "tuned", spatially localized 달팽이관 귀털의 tuning..
adaptation : fast : pacini corpuscle, meissner corpuscles, slow : merkel receptors, ruffini endings
relay nuclei : 감수기로 부터의 흥분이 시냅스를 경유해서 전달 되며 가중, 소통 억제가 진행된다.
- lateral inhibition : 감각 신경이 흥분하면 억제성중간 신경을 통해 흥분을 전한 시냅스 전신경에 되먹이 기전으로 억제성 흥분파를 보내고, 동시에 주위 감각로의 시냅스 부위에도 억제성 흥분파를 보내어 주된 흥분 주위의 주위에 있는 신경의 흥분 발사 빈도를 억제 시킨다.중추신경계
로 전달될 때 흥분 범위를 좁혀 자극의 위치나 질을 명료하게 구별할 수 있게 해주는데 중요하다.
- feed forward inhibition, feed back inhibition : 처음 center의 info도 thalamus로 가기도 하지만 relay nuclei에 의해 interneuron을 통하게 되고 interneuron은 inhibition 하게 되니가 올라갔다 inhibition하기도하고 feed back 으로 inhibition하기도 한다. sensory info가 와도 가
운데만 activate 가운데 relay nuclei에 의해 thalamus로 가고 나머지는 전달되지 못한다. inhibitory neuron에 의해 lateral sense 가 전달될 수도 있고 안될 수도 있다.
고위 중추신경계에 의해서도 이뤄지는데 이건 central / descending inhibition 이라 한다.
Somatic sense
Dorsal Root Ganglion neuron : cell body가 dorsal horn과 tissue로 뻗어나간 neuron.
Discriminative touch : size, shape, texture, movement
- messner's corpuscle : fast adaptation, superficial
- merkel cell : slow adaptation, superficial
- pacinian corpuscle : fast adaptation, deep
- ruffini ending : slow adaptation, deep
Proprioception : 눈으로 안봐도 아는 것, 고유감각
Nociception : 통증
Thermoreception : Temperature sense
dorsal column-medial lemniscal system touch, proprio : medulla => ipsilaterally
anterolateral system : pain, temperature - spinal corde(dorsal horn) => contralaterally
털 OK : hair follicle receptor
털 NO : 인곳의 messner's corpuscle, merkelcell, pacinian corpuscle, ruffini ending를 본 것.
precursor, 전구물질 : 어떤 화합물을 합성하는 데 필요한 재료가 되는 물질
Pain
Nociceptor : thermal, mechanical 은 빨리, polymodal은 C라서 느리게
- capsaicin receptor 같은게 depolarize free sonsory endings and generate action potentials is not known.
Laminae i, ii : Adelta and C fibers -> nociceptive specific neurons, respond exclusively to noxious stimulation
Laminae II : almost exclusively interneurons
Laminae III & IV : Abeta fibers -> nonnoxious
Laminae V : wide dynamic-rage neurons -> Abeta and A delta fibers, C fibers -> referred pain
referred pain 같은 곳에 nerve ending이 있어서 헷갈린다.
glutamate : neurotransmitter A delta and C
neuropeptide : No uptake mechanism
hyperalgesia(예민해진 것)
- peripheral or central - mediated by axon reflex, release of chemicals such as bradykinin, histamine, prostagladeins, leukotriens, acetylcholine, serotonin and substance P from the damaged cells and tissues in the vicinityof injury
- reason : decrease the threshold, some activate nociceptors(histamine)
- prostagladins, brad\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0ykinin
- PGED2 : a metabolite of arachidonic acid and is generated by the enzyme cyclooxygenase release from damaged cells - Aspirin
p47 그림설명
Injury - release two neuropeptides, Sub P and CGRP from nociceptive endings ->
spread of edema by acting directly on venules to produce vasodilation ->
hyperalgesia by leading to the release of histamine from mast cells ->
decreases the threshold for activation of nociceptors.
centrally mediated hyperalgesia : 오래된 고통으로 c fiber 메모리에 각인된 것.
1) Severe and persistent injury, C fibers fire repetitively ->
response of dorsal horn neurons increase - called "wind-up" ->
because of glutamate release from C fiber endings->
NMDA channel opens ->
blocking NMDA-receptor can blck wind-up
2) Noxious stimulation can produce long-term changes in dorsal horn neurons -> similar to LTP ->
called central sensitization -> a memory of the c fiber input ->
increase of gene expression, upregulation of the expression of neuropeptides and neurotransmitters, receptors.
somatic은 4개 였는데 Nociceptive는 5개.?? 이건좀 알아봐야한다.
- Spinothalamic : first synapse in the thalamus
Spinoreticular : first synapse in reticular formation of pons
Spinomesenphalic
- first synapse in periaquiductal gray matter
- project to the amygdala, - affective component of pain
Cervicothalamic : to nuclei in the "midbrain" and to "thalmus"
Spinohypothalamic
- to supraspinal autonomic control centers
- activate complex neuroendocrine and cardiovascular responses
read p51
gate control theory : nonnociceptive afferents " close" and nociceptive afferents "open" -> close 하는 걸로 억제 가능.. C는 pain A beta는 억제.. TENS로 실용?
painaqueductral gray matter : mid brain안에 있고 여기를 자극 하면 내려가고 위로올라오는 pain을 reduce한다.
opiate-induced analgesia : 아편..
- opiates-morphine and codeine - periaqueductal gray region is the most sensitive retgion
- opiate produce analgesic effect by activation the descending pain modulatory pathways
- serotonergic and noradrenergeic descending pathways inhibit nociceptor neurons by direct and indirect pathway.
endogenous opioid receptors : 몰핀이 효과가 있는데 이것에 리셉터가 있을거고 거기 리셉터가 있다면 몸속에서 ligand를 만들테고 그게 Enkephalins, beta-endorphin(product of POMC), dynorphins이 3가지다.
protein이 커야 packing이 잘된다. transport도 커야 가능하다.
Postsynaptic inhibition
Presynaptic inhibition