Ngaba Yadalwa?

Inwebu Yeliso Iretina

● Iliso lomntu lineretina—inwebu eneeseli ezimalunga nezigidi ezili-120 ekuthiwa ziiphotoreceptor, ezitshintsha imitha yokukhanya ukuze ikwazi ukuya engqondweni. Ingqondo yakho itshintsha le mitha iyenze imifanekiso. Abantu abathi izinto zazivelela bathi indlela iretina eyenziwe ngayo kwiliso lezilwanyana ezinethambo lomqolo ingqina ukuba iliso alizange lidalwe.

Khawucinge ngoku: Iiphotoreceptor zezilwanyana ezinethambo lomqolo zisemva kweretina. Ukuze imitha yokukhanya ifike kuzo, kufuneka idlule kwiiseli ezininzi. UKenneth Miller osisazi sebhayoloji esikholelwa kwindaleko uthi, “loo nto iyakuphazamisa ukuhamba kokukhanya nto leyo esenza singaboni kakuhle njengokuba bekufanele kube njalo.”

Abantu abakholelwa kwindaleko bathi iretina bubungqina bokuba izinto azizange zidalwe. Esinye isazinzulu sada sathi “ime ngendlela egqwethekileyo yaye isebenza ngendlela ebhanxekileyo.” Noko ke, uhlolisiso olungakumbi lubonisa ukuba iiphotoreceptor zeretina zikwindawo efanelekileyo kufutshane ne-epithelium—inwebu yeseli evelisa ioksijini nezakhamzimba ezikunceda ubone kakuhle. Isazi sebhayoloji uJerry Bergman nogqirha wamehlo uJoseph Calkins bathi: “Ukuba inwebu ye-epithelium ibingaphambi kweretina besingazi kubona kakuhle.”

Iretina izinceda ngakumbi izilwanyana ezinethambo lomqolo ezinamehlo amancinane. Unjingalwazi uRonald Kröger weYunivesithi yaseLund eSweden uthi: “Kufanele kubekho umgama othile phakathi kwelensi yeliso neephotoreceptor ukuze ukwazi ukubona kakuhle. Ukuvalwa kwesi sikhewu ngeeseli zemithambo-luvo kuluncedo kwizilwanyana ezinethambo lomqolo.”

Ukongezelela koko, ukubakho kweeseli zemithambo-luvo zeretina ezininzi kufutshane neephotoreceptor kukwenza ubone kakuhle.

Ucinga ntoni? Ngaba iretina ayenziwanga kakuhle ibe yazivelela ngamabona-ndenzile? Okanye ngaba yadalwa?

[Umzobo okwiphepha 15]

(Ukuba ufuna inkcazelo ehlahlelwe kakuhle, yiya kwimpapasho)

Iiseli zephotoreceptor

Ukukhanya

Iepitheliuim

Ukukhanya

Iretina

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