Umgodi noma ukuvulwa okuphakathi nendawo ye-iris yeso. Umfundi ulawula inani lokukhanya elingene iso. Usayizi wamfundi ulawulwa yi-dilator ne-sphincter imisipha ye-iris.
Isizathu Sokuba Nabafundi
Umfundi ulawula ukukhanya okungakanani okuvunyelwe ukungena esweni. Kufana kakhulu nokuvula ikhamera okuvumela ukukhanya okungaphezulu ukuze kuvezwe okwengeziwe.
Ebusuku, abafundi bethu bahlanza ukuvumela ukukhanya okwengeziwe ukuze sikhulise umbono wethu. Ebusuku obukhanyayo, umfundi wethu wehlela kancane kancane ukuze asivumele ukusebenza ngendlela evamile. Uma kungenjalo, siyobe sibucayi kakhulu. Lokhu kuvikela ama-photoreceptor avela ebucayi bethu.
Futhi, uma sibheka into ebuseduze kakhulu njengokufunda incwadi, amehlo ethu aguquka futhi abafundi bethu bahlehlise. Lapho abafundi bethu behlehliswa, kufana nokubhekelela umquba. Ukubheka emgodini omncane kunciphisa ukufiphaza komonakalo futhi kwandise ukugxila kokugxila. Lokhu kuthuthukisa ubulunga obubonakalayo jikelele. Usayizi ojwayelekile wesikole uphakathi kuka 2.5 kuya ku-4.0 mm.
Imuphi uhlelo olulawula umfundi?
Iris , ingxenye enemibala yeso lethu, yenziwe nge-pigment futhi iqukethe amasethi amabili wezinhlanzi ezibushelelezi ezilawula ubukhulu bomfundi. i-sphincter muscle nomsila we-dilator. I-sphincter muscle isesimweni sesendandatho emkhawulweni womfundi.
Uma izivumelwano, zenza noma zinciphisa ubukhulu bomfundi. Imisipha ye-dilator isesimweni esivela kuwo wonke ama-iris futhi uma isivumelwano, siphucula noma sandisa ubukhulu bomfundi.
Zomi zombili izinhlelo, izinhlelo ze-parasympathetic kanye nozwela zilawula umfundi. Uhlelo lwethu lwe-parasympathetic lulawula imisebenzi yansuku zonke njengokuphumula, ukunciphisa isilinganiso senhliziyo nezinto ezifana nokugaya.
Ilawula ubukhulu bomfundi phakathi kwemisebenzi evamile phakathi nosuku futhi ishintshe ukuphakama komfundi kuye ngokuthi kunjani ukukhanya. Uhlelo lokuzwelana luyisistimu yokuzivikela futhi lusinika izimpendulo ezivamile zokulwa noma izindiza. Kulo mfundi, uma sesaba noma sisaba, abafundi bethu bahlanza kakhulu. Lokhu kucatshangelwa ukuthi kuvumele ukukhanya ngakho izimpendulo zethu zishesha.
Okubalulekile ekunakekelweni kwezempilo
Ukuhlolwa komfundi kubaluleke kakhulu emithini yezokwelapha ngoba indlela yezinzwa zomfundi eyenziwa yizinzwa ezintathu ezihlukene futhi ilandela indlela ende kakhulu emzimbeni. Le ndlela emithathu ye-neuron iqala engxenyeni yobuchopho okuthiwa i-hypothalamus futhi ihamba phansi intambo yomgogodla. I-neuron yesibili iphuma emthonjeni womgogodla uhamba ngaphezu kwephaphu bese iphakamisa intamo lapho ihlangana ne-neuron yesithathu.
Kusukela lapha kuya ngaphansi komcibisholo we-subclavia bese ushaya ukuhamba eceleni kwe-artery carotid bese uphindela emuva ebuchosheni nasweni. Ngenxa yendlela yayo ende, odokotela basebenzisa lo mfundi ukuhlola ukuthi kungenzeka yini ukuphazamiseka okungase kuthinte le ndlela. Isibonelo, umdlavuza wamaphaphu othinta phezulu emaphashini lapho inzwa yomfundi ehamba khona kungathinta umsebenzi we-pupillary.
Kuncike ekulahlekelweni komsebenzi umfundi abonisa, ngezinye izikhathi bangatshela ukuthi bangabheka kuphi umdlavuza.