Iris yiyona ingxenye enemibala yeso elilawula isibalo sokukhanya esingena esweni. Yingxenye ebonakalayo kakhulu iso. Iris ihlezi phambi kwe- lens crystalline futhi ihlukanisa ifomu lekamelo langaphakathi lekamelo eliphansi. Iris engxenyeni ye-uveal tract ehlanganisa umzimba we-ciliary obuye ube ngemuva kwe-iris.
Izicubu ze-iris zenza umfundi.
Umfundi ungumgodi we-iris lapho ukukhanya kudlulela khona emuva kweso. Iris ilawula ubukhulu bomfundi. Umfundi empeleni utholakala nesikhungo saso kancane ngezansi futhi kancane kancane ohlangothini lwangasese we-cornea.
Usayizi womfundi
Ubukhulu bomfundi bulawulwa yimisipha emibili e-iris. I-sphincter pupillae iyakhela umngcele womfundi futhi uma izivumelwano, umfundi ehla ngesayizi. Lokhu kubizwa ngokuthi i-miosis. Isisu sesibili esilawula usayizi wesiphakamiso yi-dilator pupillae. Le misipha iqukethe izintambo ezihlelwe nge-radial pattern iris. Uma izivumelwano, lo mfundi ehlisa noma ekhulisa ngosayizi. Lokhu kubizwa ngokuthi i-mydriasis.
Uhlelo lwe-parasympathetic lulawula i-sphincter pupillae nesistimu enozwela ilawula i-dilator pupillae. Kukhona uxhumano phakathi kwalezi zinhlanzi kulokho umsila we-dilator kufanele ukhululeke ukuvumela i-sphincter ukuba igxile umfundi.
Ubukhulu bendawo yobufundi bendawo kusuka ku-2 kuya ku-4 mm ngobubanzi ekukhanyeni ku-4 kuya ku-8 mm ebumnyameni.
Umbala we-Iris
Umbala we-Iris uxhomeke enani le- melanin pigment ku-iris. Umuntu onamehlo ensundu unombala ofanayo we-melanin pigment ukuthi umuntu onamehlo aluhlaza okwesibhakabhaka unayo. Noma kunjalo, umuntu onamabala aluhlaza okwesibhakabhaka unemibala engaphansi kakhulu.
Ingemuva kwe-iris ivame ukugqunywa kakhulu ukuze kuvinjelwe ukukhanya kusuka ekukhanyeni iris.
Amaphethini efa ye-iris umbala indawo efundela kakhulu. Umbala wamehlo ulawulwa yizakhi zofuzo eziyisisekelo eziyisithupha. Abacwaningi baqonda ezimbili zalezi zakhi zofuzo kahle futhi enye yazo isengumfihlakalo. Lezi zakhi zofuzo zilawula ukuthuthukiswa kombala wesibhakabhaka ohlaza, obomvu nesibhakabhaka. Grey, hazel, nezinye izinhlanganisela kunzima ukubikezela. Kweminye imindeni, ifa lebala leso lilandela amaphethini alindeleke kakhulu kanti, nakweminye imindeni, kubonakala ingenangqondo noma ilandela imithetho. Kuzofuzo, lokhu kubizwa ngokuthi "i-polygenic." I-Polygenic isho ukuthi kungase kube nezakhi zofuzo eziyinkimbinkimbi ezithintekayo ezibandakanya ukwenza umbala weso. Ukusho nje ukuthi umbala obomvu ungaba obala okwesibhakabhaka kwenza izincazelo ezilula, kodwa lo mzekelo ulula kakhulu kuzo zonke izinhlobo ezibonakala ekuphileni kwangempela.
Ukungahleleki kwe-Iris & Nomfundi
Izinkinga ze-Iris kanye nezifundi zifaka:
- I-Aniridia - Aniridia yisici esingokwemvelo lapho umuntu ezalwa ene-iris.
- I-Coloboma - I-iris coloboma iyimbobo enkulu e-iris
- IsiSwidi - Isi-synechia ukunamathela okwenzeka phakathi kwe-lens ne-iris
- I-Corectopia - i-Corectopia yilapho umfundi evulekile khona isikhungo
- I-Dyscoria - i-Dyscoria yinkinga lapho umfundi ephikisiwe noma engavamile futhi engahlali ngokujwayelekile