INzwa

umdwebo wenZwa

Inzwa noma ingqamuzana lenzwa liyingqamuzana elikhabathiswa ngamazuba aqanguza namanya amangqamuzana ngezixhumo zekhethelo ezibizwa amanombe (synapses). Inzwa iyisigcoyi esiyinhloko sesicubu senzwa kuzo zonke izilwane ngaphandle kweziphilincinci ezithile. Izinto okungezona izilwane njengezimila nokhunta azinawo amangqamuzana enzwa.

Izinzwa imvama zinjinjwa zibe izinhlobo ezintathu ngokwemisebenzi yazo. Izinzwa zokuzwa (sensory neurons) ezisabela evusweni elinjengokuthintwa, umsindo, noma ukukhanya okuthinta amangqamuzana ezitho zokuzwa, bese wona athumela iziyabizo emhlandleni noma ebuchosheni. Izinzwa zokudikiza (motor neurons) zamukela iziyabizo ezisuka ebuchosheni nasemhlandleni zokulawula konke kuqala ekufinyezweni kwemisipha kuya ekutshokozeni kwezindlala. Izinzwa ezixhumayo (internuerons) zixhuma izinzwa kanye nezinzwa maphakathi nendawo eyodwa esebuchosheni nona emhlandleni. Lapho izinzwa eziningi zixhumene ndawonye zakha lokho okubizwa ngomthandelo wezinzwa.

Izinzwa ezivamile ziqukethe umzimba wenZwa, amakleleba (dendrites), noluzi olulodwa (single axon). Umzimba unguhlaka oluyisiyingili, bese uluzi namakleleba kube izinkosa eziphuma kuwo umzimba. Amakleleba imvama aba ngamagatsha futhi ajijeka ibanga elingamamithancinci (micrometers) ayikhulu kusuka emzimbeni. Uluzi luphuma emzimbeni ngesiqatha esibizwa imbanda yoluzi (axon hillock) futhi lungaba imitha elilodwa kubantu noma ukweqa kweminye imiqhinqo. Luyaxhantela kodwa kodwa luvame ukugcina ilungangoni (diameter) elifanayo. Esihlokweni samagatsha oluzi kukhona imidiyo yoluzi (axon terminals), lapho Inzwa ifufukisa khona iziyabizo ngamanombe eziya kwamanje amangqamuzana. Izinzwa kwesinye isikhathi ziswela amakleleba noma uluzi.