Zitsanzo za Mafunso Okhudza Njira Yopangira Mitsempha
Njira yolumikizira mitsempha ndi gawo lofunika kwambiri la dongosolo lamanjenje, zomwe zimathandiza kuti maselo a mitsempha azilumikizana komanso pakati pa maselo a mitsempha ndi ziwalo zina za thupi. Kumvetsetsa lingaliro ili ndikofunikira kwambiri pophunzira za kachitidwe ka thupi, kaya pa maphunziro apamwamba, kafukufuku, kapena ntchito zothandiza m'dera lazaumoyo. Nkhaniyi ifotokoza mfundo yoyambira ndikupereka zitsanzo zingapo za mavuto ndi mayankho kuti akuthandizeni kumvetsetsa njirayi.
Pendauluan
Dongosolo la mitsempha limapangidwa ndi ubongo, chingwe cha msana, ndi netiweki ya mitsempha yomwe imagawidwa m'thupi lonse. Ntchito yake yayikulu ndikulandira zolimbikitsa, kukonza chidziwitso, ndikutumiza malamulo ku minofu ndi tiziwalo ta m'mimba. Kuthamanga kwa mitsempha ndi zizindikiro zamagetsi zomwe zimathandiza kulankhulana mwachangu komanso moyenera mkati mwa dongosolo la mitsempha.
Kuthamanga kwa mitsempha, kapena mphamvu ya kuchitapo kanthu, kumachitika chifukwa cha kusintha kwadzidzidzi kwa mphamvu yamagetsi kudutsa nembanemba ya selo ya mitsempha (neuron), komwe kumachitika chifukwa cha kuyenda kwa ayoni a sodium (Na+) ndi potaziyamu (K+) kudutsa nembanemba. Njirayi imayamba pamene neuron imalandira mphamvu yokwanira (yopitirira malire ake), zomwe zimayambitsa zochitika zingapo zamagetsi ndi mankhwala.
Chiphunzitso Choyambirira cha Njira Yopangira Mitsempha
1. Mphamvu Yopumula: Mu nthawi yopumula, mkati mwa neuron mumakhala ndi mphamvu yoipa poyerekeza ndi kunja kwake. Mphamvu yopumula iyi nthawi zambiri imakhala pafupifupi -70 mV, zomwe zimatsimikiziridwa ndi kufalikira kwa ma ayoni a Na+ ndi K+ okhala ndi Na+ yambiri kunja kwa selo ndi K+ mkati mwa selo.
2. Kuchepetsa mphamvu ya maselo: Pamene minyewa ya ubongo yalandira mphamvu zokwanira, njira za Na+ ion zimatseguka, zomwe zimapangitsa kuti Na+ ilowe mu selo. Izi zimapangitsa kuti mkati mwa selo mukhale ndi mphamvu zambiri, ndipo ngati pakufunika kutero, mphamvu ya maselo imayamba kugwira ntchito.
3. Kubwezeretsa mphamvu: Pambuyo poti mphamvu ya Na+ yafika pachimake, njira za Na+ zimayamba kutseka ndipo njira za K+ zimatseguka, zomwe zimapangitsa kuti K+ ituluke mu selo, kotero kuti mphamvuyo imabwerera kukhala yoipa mkati mwa selo.
4. Hyperpolarization ndi Refractory Potential: Nthawi zina, kutulutsidwa kwa K+ kumapangitsa kuti membrane potential ikhale yoipa kwambiri kuposa pa nthawi yopuma, yotchedwa hyperpolarization. Mu gawo la refractory potential, neuron singathe kapena imakhala ndi vuto lalikulu kuyambitsa mphamvu yatsopano yogwira ntchito.
5. Pampu ya Sodium-Potaziyamu: Pambuyo pa mphamvu yogwira ntchito, pampu iyi imabwezeretsa kugawa kwa ayoni ku mkhalidwe wake woyambirira mwa kupompa Na+ kutuluka ndi K+ kubwerera mu selo.
Mafunso ndi Kukambirana Zitsanzo
Funso 1
Fotokozani momwe mphamvu yogwirira ntchito imayambitsidwira komanso momwe imafalikira kudzera mu neuron.
Kukambirana:
Mphamvu ya kuchitapo kanthu imayamba pamene neuron imalandira mphamvu yokwanira kufika kapena kupitirira malire ake a depolarization, omwe nthawi zambiri amakhala pafupifupi -55 mV. Malire awa akafika, njira za sodium ion zomwe zimakhala ndi mphamvu yamagetsi zimatsegulidwa, zomwe zimapangitsa kuti ma Na+ ion asunthire mwachangu mu neuron. Izi zimapangitsa kuti gawo la nembanemba ya neuron liwonongeke, zomwe zimapangitsa kuti likhale labwino kwambiri.
Pambuyo poti depolarization yafika pachimake, njira za sodium ion zimatseka ndipo njira za potassium ion zomwe zimakhala ndi mphamvu yamagetsi zimatseguka, zomwe zimathandiza kuti ma K+ ion ayende kuchokera mkati mwa neuron kupita kunja. Njira imeneyi imadziwika kuti repolarization, pamene nembanemba imabwerera ku mphamvu yake yopuma yoipa kwambiri. Kuthamanga kwa mitsempha kumafalikira kudzera mu njira yokonzanso kudzera mu axon, komwe njira zotsatizana za depolarization ndi repolarization zimachitika m'magawo osiyanasiyana a nembanemba ya neuron.
Funso 2
Kodi mphamvu yotsutsa mphamvu ya ubongo (refractory potential) imagwira ntchito yotani podziwa komwe mphamvu ya mpweya imayendera mu axon ya neuron?
Kukambirana:
Mphamvu yokana imakhala ndi magawo awiri: absolute ndi relative relative. Mu gawo lokana kwathunthu, neuron singathe kusonkhezeredwa kuti ipange mphamvu yatsopano yochitapo kanthu, ngakhale mphamvu ya stimulus ikhale yamphamvu bwanji. Izi zimachitika pamene njira za Na+ sizigwira ntchito ngakhale depolarization itatha. Mu gawo lokana, mphamvu yatsopano yochitapo kanthu imatha kuyambika, koma imafuna mphamvu yolimbikitsira chifukwa nembanemba imakhala ndi hyperpolarized.
Mphamvu yokana kusuntha ndi yofunika kwambiri poonetsetsa kuti mitsempha ya mitsempha ikuyenda mbali imodzi yokha motsatira axon. Gawo la axon likangochepa mphamvu, limalowa mu nthawi yokana kusuntha, zomwe zimalepheretsa kuti mitsempha isabwerere m'mbuyo. Motero, mitsempha imatha kuyenda patsogolo kupita ku gawo lotsatira, lomwe lidakali pa mphamvu yopuma ndipo silinayambe kugwira ntchito. Njirayi imatsimikizira kuti zizindikiro za mitsempha zimatumizidwa bwino ku axon terminal kumapeto kwa neuron.
Funso 3
Kodi chingachitike n’chiyani ngati ntchito ya pampu ya sodium-potassium itasokonekera mu neuron? Fotokozani momwe mphamvu yopumulira imakhudzira.
Kukambirana:
Pampu ya sodium-potassium (Na+/K+ ATPase) imagwira ntchito yofunika kwambiri posunga mphamvu yopuma ya ma neuron mwa kutulutsa ma ayoni atatu a Na+ ndi ma ayoni awiri a K+ mu selo. Njirayi imafuna mphamvu kuchokera ku ATP ndipo imasunga kuchuluka kwa ma concentration komwe ndikofunikira kuti ma neuron azigwira ntchito bwino.
Ngati ntchito ya pampu iyi yasokonekera, kufalikira kwa ma ayoni a Na+ ndi K+ mkati ndi kunja kwa neuron kudzasintha, ndipo ma ayoni ambiri a Na+ adzasonkhana mkati mwa selo ndi K+ yambiri kunja kwa selo. Izi zidzapangitsa kuti mphamvu yopumira iwonongeke, zomwe zingapangitse kuti neuron ikhale yofulumira kwambiri kapena kulepheretsa kupanga mitsempha chifukwa neuron singabwerere ku mphamvu yake yopumira. Kuphatikiza apo, kusalinganika kwa ma ayoni kungasokoneze ntchito yamagetsi ya ma neuron ena ndipo kungayambitse mavuto monga khunyu, arrhythmias, kapena kuwonongeka kwina kwa maselo a mitsempha.
Mapeto
Kumvetsetsa njira yogwirira ntchito kwa mitsempha kumafuna kudziwa bwino za kapangidwe ka mitsempha ya mitsempha, kugawa kwa ma ayoni, ndi ntchito ya mapuloteni a membrane monga njira za ion ndi mapampu a sodium-potassium. Kumvetsetsa kumeneku kumatithandiza kumvetsetsa bwino njira za mitsempha ndi matenda osiyanasiyana omwe angachitike. Mwa kuchita zinthu motsatira mavuto, kumvetsetsa kwathu njira imeneyi kungalimbitsidwe, motero kumatikonzekeretsa bwino mafunso amtsogolo a maphunziro ndi zochitika zachipatala.
