Indlela Yokusebenza Okungenzeka Kumaseli Emizwa
I-Pendahuluan
Amaseli emizwa, noma ama-neurons, ayisisekelo sesimiso sezinzwa futhi asebenza ukudlulisa ulwazi kuwo wonke umzimba. Enye yezindlela eziyinhloko ezenza lokhu kudluliswa kolwazi yikhono lokusebenza. Amandla okwenza isenzo ushintsho olusheshayo nolwesikhashana ku-voltage ye-membrane yeseli lezinzwa evumela isignali kagesi ukuthi ihambe nge-axon isuka komunye umkhawulo we-neuron iye komunye. Lesi sihloko sizohlola ngokucophelela izindlela eziyisisekelo, inqubo yokugeleza kwama-ion eyisisekelo, kanye nezigaba ezihilelekile enkambisweni yokusebenza kwamandla.
Isakhiwo Esiyisisekelo Sama-Neuron
Ngaphambi kokuqonda indlela yokusebenza kwamandla esenzo, kubalulekile ukuqonda isakhiwo esiyisisekelo sama-neurons ngokwawo. Ama-neurons anezingxenye ezintathu eziyinhloko: i-soma (umzimba weseli), ama-dendrite, nama-axon.
– Soma: Lona umzimba oyinhloko we-neuron, oqukethe i-nucleus kanye nezinye i-organelles. I-soma iyisikhungo somsebenzi we-metabolism we-neuron.
– Ama-dendrite: Lawa ama-fiber amafushane, anamagatsha athola izimpawu ezivela kwamanye ama-neuron bese ezidlulisela ku-soma.
– I-Axon: Isakhiwo eside, esincane esidlulisela izimpawu ezivela ku-soma ziye kwamanye ama-neurons noma kumaseli asebenzayo.
Ekugcineni kwe-axon kukhona i-axon terminal, lapho ama-neurotransmitter ekhishwa khona angene ku-synapse, abese ethinta i-neuron eqondiwe.
I-Electrophysiology Eyisisekelo
I-voltage ye-membrane iyisici esibalulekile endleleni yokusebenza kwamandla okusebenza. Ngaphansi kwezimo zokuphumula, ama-neurons anamandla okuphumula kwe-membrane angaba ngu--70 mV. Lokhu kusho ukuthi ingaphakathi leseli alibi kakhulu kunelangaphandle. Leli khono likhiqizwa ukusatshalaliswa kwama-ion njenge-sodium (Na+), i-potassium (K+), i-chloride (Cl-), kanye nama-anion e-organic ngaphakathi nangaphandle kweseli, okulawulwa yi-plasma membrane engangeni kahle.
Iphampu ye-sodium-potassium (Na+/K+ ATPase) idlala indima ebalulekile ekugcineni lokhu kusabalala kwama-ion. I-molecule ngayinye ye-ATP e-hydrolyzed iphampa ama-ion amathathu e-sodium ngaphandle kweseli kanye nama-ion amabili e-potassium angene esitokisini, igcina i-gradient ye-electrochemical.
Indlela Engenzeka Yesenzo
Isigaba 1: Ukususwa kwe-polarization
Amandla esenzo aqala lapho i-neurite (i-dendrite noma umzimba weseli) ithola isikhuthazo esinamandla ngokwanele ukufinyelela umkhawulo (-55 mV). Njengoba amandla e-membrane esondela kulo mkhawulo, iziteshi ze-sodium ezivalwe ngogesi ezitholakala ku-axon membrane ziqala ukuvula. Ama-ion e-sodium, akhona ngamanani aphezulu ngaphandle kweseli, angena ngokushesha ku-neuron, okubangela ukuqedwa okusheshayo kwe-neuronal membrane. Lokhu kubangela ukuthi ingaphakathi le-neuron libe ngcono, lifinyelele cishe ku-+30 mV.
Isigaba 2: Amandla Okwenza Okukhulu Kakhulu
Uma ulwelwesi lufinyelela cishe ku-+30 mV, iziteshi ze-sodium ziqala ukuvala ngokuzenzakalelayo futhi iziteshi ze-potassium ezivalwe ngogesi ziqala ukuvula. Kuleli qophelo, isiqongo samandla esenzo sesifinyelelwe.
Isigaba 3: Ukuguqulwa kwesimo se-polarization
Ngemva kokufika kwesilinganiso esiphezulu samandla okwenza isenzo, i-neuron iqala ukubuyisela amandla ayo e-membrane esimweni sayo sokuphumula. Lapho iziteshi ze-potassium ezivalwe ngogesi zivuleka, ama-ion e-potassium, akhona ngokugxila okuphezulu ngaphakathi kweseli, aqala ukuphuma ku-neuron. Lokhu kukhululwa kwe-K+ kubangela ukuthi i-membrane ye-neuron ibe yimbi kakhulu, inqubo eyaziwa ngokuthi i-repolarization.
Isigaba 4: Ukwanda kwe-Hyperpolarization kanye nokubuyiselwa kwemali
Ngezinye izikhathi, ukuphuma kwama-ion e-potassium ngokweqile kubangela ukuthi ulwelwesi lube lubi kakhulu kunekhono lalo lokuphumula elijwayelekile (ngaphansi kuka--70 mV), isigaba esaziwa ngokuthi i-hyperpolarization. Ngesikhathi se-hyperpolarization, i-neuron ingena esikhathini esiphelele bese kuba yisikhathi sokungaphenduli kahle, lapho isabela kancane noma kancane ezicini ezintsha. Iphampu ye-sodium-potassium ibe isibuyisela ngempumelelo ukusatshalaliswa kwama-ion esimweni sokuphumula esizinzile.
Isigaba 5: Ukuqhutshwa Kwesenzo Okungenzeka
Ngemva kokuba ingxenye eyodwa yolwelwesi lwe-axon iphukile, amandla esenzo asakazeka eduze kwe-axon njengegagasi. Iziteshi ze-sodium ezingxenyeni ezilandelayo zolwelwesi lwe-axon zivuleka ngokulandelana. Le nqubo ivumela isignali kagesi ukuthi isakazeke kahle esigungwini se-axon.
Kuma-neurons ane-myelin sheaths, ukuqhutshwa kwamandla esenzo kusebenza kahle kakhulu ngenqubo ebizwa ngokuthi i-saltatory conduction, lapho amandla esenzo "egxuma" esuka kwelinye i-node le-Ranvier iye kwelinye. I-Myelin isebenza njengesivikelo, ivimbela ukuvuza kwama-ion, ngaleyo ndlela isheshise ukudluliswa kwesignali.
Ukufaneleka Kwemvelo Nokwelashwa
Izindlela zokusebenza ezingaba khona azigcini nje ngokuyisisekelo imisebenzi eyisisekelo yesimiso sezinzwa kodwa futhi zibalulekile ezimweni ezahlukahlukene zezokwelapha nezomzimba. Isibonelo, ukuphazamiseka kweziteshi ze-ion kungaholela ezifweni ezahlukahlukene zezinzwa ezifana ne-multiple sclerosis, isifo sokuwa, kanye nezinye izinhlobo ze-neuropathy.
I-Multiple Sclerosis (MS): Ku-MS, i-myelin sheath emboza ama-axon yonakaliswa isimiso somzimba sokuzivikela. Lokhu kuphazamisa ukuhanjiswa kwe-saltatory, okubangela ukuthi izimpawu zemizwa zihambe kancane noma zime ngokuphelele.
Isifo Sokuxhuzula: Lesi simo sivame ukubangelwa ukungasebenzi kahle kwesiteshi se-ion okubangela ukuthi umsebenzi wezinzwa usebenze ngokweqile futhi ungalawuleki, okuholela ekuxhuzuleni.
I-Neuropathy: Ezinye izinhlobo ze-neuropathy zivela ekulimaleni noma ukungasebenzi kahle kwe-myelin sheath noma amaseli ezinzwa ngokwawo, okuphazamisa ukudluliselwa kwamandla esenzo, okuholela ezimpawini ezifana nobuhlungu, ukungazweli, noma ubuthakathaka.
Isiphetho
Amandla okwenza isenzo ayinto eyinkimbinkimbi kodwa ebalulekile ye-electrophysiological yokusebenza kwesistimu yezinzwa. Le nqubo ihilela uchungechunge lwezigaba ezisukela ekuqedeni i-polarization, amandla okwenza isenzo esiphezulu, ukuphinda kusebenze, kanye ne-hyperpolarization, konke kulawulwa yi-ion channel dynamics. Ukuqonda lezi zindlela akugcini nje ngokuhlinzeka ngokuqonda okuyisisekelo kokuthi ulwazi ludluliselwa kanjani ohlelweni lwezinzwa kodwa futhi kunikeza isisekelo sokuqonda nokuthuthukisa izindlela zokwelapha zezimo ezahlukahlukene zezinzwa.
Ngolwazi olukhula njalo kulo mkhakha, amathuba okuthola izindlela zokwelapha ezisebenzayo kakhulu zezinkinga zesimiso sezinzwa ayakhula, okuletha ithemba elisha ezigulini eziningi emhlabeni jikelele.
