Hanganga me te Mahi a ngā Pūtau Schwann
Ko ngā pūtau Schwann he momo pūtau glial (pūtau tautoko) e kitea ana i roto i te pūnaha io peripheral (PNS). He mea nui tā rātou mahi matua nā te mea ko rātou te kawenga mō te hanganga myelin, te tiaki axon, me te āwhina i te whakatikatika io i muri i te whara. Ki te kore ngā pūtau Schwann, kāore e taea e ngā nekehanga io te haere me te tere me te whai hua e hiahiatia ana e te tinana hei whakarite i te nekehanga, te kare ā-roto, me ngā mahi okana. Ka matapakihia e tēnei tuhinga te hanganga o ngā pūtau Schwann, me pēhea tā rātou mahi, me ngā mahi matua e mea nui ai rātou ki te hauora o ngā io.
Te whakamāramatanga me te tūranga o ngā pūtau Schwann i roto i te pūnaha io
I roto i te pūnaha io, ka mahi ngā pūtau glial hei "rōpū tautoko" mō ngā neurons. I roto i te pūnaha io matua (CNS), pērā i te roro me te taurakira, ka hangaia te myelin e ngā oligodendrocytes. I taua wā, i roto i te pūnaha io taha, ka taka tēnei kawenga ki ngā pūtau Schwann. Ka piri ngā pūtau Schwann ki ngā axons neuronal, ā, mā roto i ngā tikanga motuhake, ka takai i a rātou, ka hanga he paparanga myelin, he paparanga tiaki rānei, i runga i te momo axon e mahi ana rātou.
Ka kitea ngā pūtau Schwann i roto i te nuinga o ngā io ā-taha, tae atu ki ngā io pūoko (e kawe ana i ngā mōhiohio mai i ngā kaiwhakawhiwhi ki te roro), ngā io nekeneke (e kawe ana i ngā whakahau mai i te roro ki ngā uaua), me ngā io ā-roto (e whakahaere ana i ngā whekau o roto me te kore e mōhio).
Hanganga taketake o ngā pūtau Schwann
I te nuinga o te wā, he hanganga tō ngā pūtau Schwann e rite ana ki tā rātou mahi hei hipoki me te tautoko i ngā axon. Ko ētahi o ā rātou wāhanga nui ko:
1. Te tinana pūtau me te karihi pūtau
Kei ngā pūtau Schwann ngā karihi e tū ana i te taha o te pūtau, inā koa i te wā e hanga ana te pūtau i te myelin. E pā ana tēnei tūranga "taha" o te karihi ki ngā koiri kiriuhi hanga myelin maha i ētahi atu wāhi.
2. Te kiriuhi toto e karapoti ana i te axon
Ko te āhuatanga matua o ngā pūtau Schwann ko tō rātou kaha ki te takai i ngā axon. Ka takai tonu te kiriuhi plasma i te axon hei hanga i tētahi paparanga maha-paparanga, whai ngako. Ka kiia tēnei paparanga ko te pūkahu myelin, e mahi ana hei ārai hiko.
3. Te angaanga o te pūtau me ngā wāhanga o roto
Pērā i ētahi atu pūtau, he cytoplasm kei ngā pūtau Schwann me ngā whekau (mitochondria, endoplasmic reticulum, Golgi apparatus) hei whakaputa pūngao me te whakahaere i te hanga pūmua. He mea nui ētahi pūmua mō te pumau o te myelin me te whakawhitiwhiti kōrero ki ngā axons.
4. Papa turanga (papa turanga)
Ko tētahi āhuatanga nui o ngā pūtau Schwann ko te noho mai o tētahi lamina basal e karapoti ana i ngā pūtau. He mahi tēnei paparanga hei tautoko hanganga, hei tautoko i te pūtau, ā, he mea nui hoki mō te whakaora i ngā io i muri i te whara. Tērā pea ka mahi te lamina basal hei "rēri", hei ara rānei, hei āwhina i te tipu anō o te axon.
Ngā momo pūtau Schwann i runga i te mahi
Kāore ngā pūtau Schwann e hanga i te myelin i ngā wā katoa. E rua ngā kāwai matua:
1. Ngā pūtau Schwann e whakapūmau ana i te myelination (ngā pūtau Schwann e whakapūmau ana i te myelination)
Ko te myelin o te pūtau Schwann kotahi e takai ana i tētahi wāhanga kotahi o te axon. Mā tēnei wehenga ka hangaia he āputa iti i waenganui i ngā pūkahu myelin e kiia nei ko ngā pona o Ranvier. He mea nui ngā pona o Ranvier mō te tuku tere o ngā hihiri mā te kawe saltatory (ka "peke" ngā hihiri mai i tētahi pona ki tētahi atu).
2. Ngā pūtau Schwann kāore e hono ana i te myelin (ngā pūtau Schwann kāore e hono ana i te myelin)
I roto i ngā axon iti te whānui, kāore ngā pūtau Schwann e hanga i te myelin matotoru, engari ka whakarōpūhia ētahi axon ki roto i ngā "paihere" e kiia nei ko ngā paihere Remak. Ahakoa kāore he myelin, ka tautoko tonu ngā pūtau Schwann i te pākia o te tinana me te tiaki i ngā pūtau.
Te hanganga o te myelin me ngā pona o Ranvier
He paparanga kiriuhi momona-ngako te hanganga myelin, ā, he ārai tēnei. Ka whakaitihia e tēnei paparanga te turuturu o te iahiko hiko mai i te axon, ā, ka tere ake te tuku i ngā pūmanawa mahi. I roto i ngā io myelinated, kāore ngā nekehanga e haere tonu, engari "peke" i waenga i ngā pona o Ranvier. He tere ake, he pai ake hoki te whakamahi i tēnei kawe tote i te haere i te kiriuhi axon katoa.
Hei tāpiritanga, kei reira ngā wāhi motuhake kei runga i te axon e tata ana ki te pūnga, pērā i te paranode me te juxtaparanode, he nui ngā pūmua hongere katote me ngā pūmua piri. He mahi tā ngā pūtau Schwann ki te pupuri i tēnei whakaritenga hanganga moroiti hei pupuri i ngā tohu io pumau.
Ko te mahi matua a ngā pūtau Schwann
1. Ka hanga i te myelin, ka whakateretere i te tuku iri
Ko tana mahi tino rongonui ko te hanganga o ngā pūkahu myelin i runga i ngā io ā-taha. Ka tino whakanuia e te myelin te tere o te tuku i ngā kare ā-roto. Mā tēnei ka taea te tere me te tika o ngā urupare nekeneke (hei tauira, te tango i te ringa ina pāngia e te wera) me te tukatuka i ngā kare ā-roto (te rongo i te pā māmā).
2. Te wehewehe me te tiaki i ngā axon
He ārai hiko te mahi a te myelin, ā, ko ngā pūtau Schwann anō hoki hei tiaki ā-tinana i ngā axon. Mā tēnei tiaki ka kaha ake te ātete o ngā axon ki ngā raruraru o te taiao kiko e karapoti ana.
3. Tautoko pākia o ngā neurons
He nui te hiahia mō te pūngao o ngā neuron, ā, ka roa rawa ngā axon. Mā ngā pūtau Schwann ka āwhina i ngā axon kia whiwhi tautoko pākia mā te whakawhitiwhiti matūkai me ngā tohu ngota. He mea nui tēnei mahi mō te oranga roa o te mahi axon.
4. Te whakaoranga o ngā io i muri i te whara
Ko tētahi o ngā painga o te pūnaha io taha i runga i te pūnaha io matua ko tōna kaha whakahou pai rawa atu. He mahi nui tā ngā pūtau Schwann i roto i tēnei tukanga mā roto i ētahi wāhanga:
– Te wehewehe i te rerekētanga me te tipu haere: i muri i te whara, ka huri ngā pūtau Schwann huri noa i te wāhi kua pakaru hei āhua e tautoko ana i te whakatikatika, kātahi ka tipu haere.
– Te horoi i ngā para myelin: Ka mahi tahi ngā pūtau Schwann me ngā macrophage ki te horoi i ngā para myelin ka ārai i te whakahoutanga.
– Te Hanga i ngā "Rohe o Büngner": Ka whakarite ngā pūtau Schwann i a rātou anō hei hanga i tētahi ara hei ārahi i te tipu anō o ngā axon ki ō rātou ūnga.
– Te huna i ngā āhuatanga tipu io: Ka whakaputahia e ngā pūtau Schwann ngā ngota pēnei i ngā neurotrophins me ētahi atu āhuatanga tipu e whakaoho ana i te roa o te axon.
Ki te kore he tautoko mō ngā pūtau Schwann, ka puhoi ake te whakahoutanga o te axon i roto i te PNS, ā, ka iti ake te whakahaere.
5. Whakahaere i te whanaketanga me te pakeketanga o ngā io
He mea nui anō hoki ngā pūtau Schwann mai i te whanaketanga o te kukune tae noa ki te pakeketanga. Ka āwhina rātou ki te whakapakari i ngā hononga io, ka whakatau ko ēhea axon ka whakapūmautia ki te myelin, ā, ka whakarerekē i te matotoru o te myelin kia rite ki te rahi o te axon. He whanaungatanga hihiri tēnei: ka tukuna e ngā axon ngā tohu ki ngā pūtau Schwann, ā, ka tukuna e ngā pūtau Schwann he urupare e pā ana ki te pumau me te mahi a te axon.
6. Te tūranga i roto i te pūnaha ārai mate me te urupare mumura ā-rohe
I raro i ētahi āhuatanga, ka taea e ngā pūtau Schwann te whai wāhi ki ngā urupare ārai mate ā-rohe. Ka taea e rātou te whakaputa i ngā ngota tohu e kukume ana i ngā pūtau ārai mate, e whakahaere ana rānei i te mumura. He mea nui tēnei i roto i te horopaki o te whara me te mate o te io ā-taha.
Te hiranga haumanu: ina ngoikore ngā pūtau Schwann
Ka taea e te kino, te kore rānei e mahi tika o ngā pūtau Schwann te arahi ki te neuropathy peripheral. Hei tauira:
– Te mate Guillain-Barré (GBS): he mate pūnaha ārai mate e whakaeke pinepine ana i te myelin i roto i te PNS, ka hua ake te ngoikore o te uaua me ngā raruraru o te rongo.
– Charcot–Marie–Tooth (CMT): he rōpū mate ira ka uru pea ki te hanganga myelin ngoikore, ki te mahi rānei a te pūtau Schwann, ka hua ake te ngoikore o te uaua o te pito tawhiti me ngā raruraru haere.
– Neuroma me te schwannoma: ngā pukupuku e ahu mai ana i ngā pūtau Schwann, he pai te nuinga engari ka taea te pēhi i ngā hanganga io me te whakaputa tohu.
He mea nui te mārama ki ngā pūtau Schwann mō te rangahau i ngā maimoatanga whakaora io, te hangarau kiko, me te whakawhanaketanga rongoā mō ngā mate demyelinating.
Whakamutunga
He wāhanga nui ngā pūtau Schwann o te pūnaha io taha. I roto i te hanganga, he kaha ahurei tō ēnei pūtau ki te takai i ngā axon, ki te hanga i te myelin, me te whakarato i te lamina basal, he mea nui mō te pumau me te whakahoutanga. I roto i te mahi, ka tere ake te tuku i ngā kare ā-roto mā te kawe i ngā axon, ka tiaki i ngā axon, ka tautoko i te pākia o ngā neuron, ka whakahaere i te whanaketanga o ngā io, ā, ka whai wāhi nui ki te whakatikatika i ngā io taha i muri i te whara. Mā te mārama ki te hanganga me te mahi a ngā pūtau Schwann, ka taea e tātou te mārama ake ki te mahi a ngā io me te whakawhanake i ngā rautaki hauora hei whakatika i ngā mate io taha.
