Impilo, Imithi
Umbala kwesikhumba womuntu kuncike kulokho? sombala i-melanin
Abantu abafani: abamnyama, abamhlophe, ensundu ngisho kusukela ukukhanya ebumnyameni. Ibala kuhluka izwekazi beya zwekazi. Uvela lokhu kuhlukahluka ngokunikeza? Yini enquma umbala kwesikhumba yomuntu? Kuyini i-melanin? Asivume.
Melanin. Kuyini lokhu?
Uma sikhuluma kukhulunywa ngezokwelapha lokho melanin - lo mbala ukuthi kuhlelwe kunamaqoqo amangqamuzana esikhumba okuthiwa melanocytes. Kazi yena ekhona omningi walo izilwane, kuhlanganise nabantu. Inikeza isikhumba sombala i-melanin ezihlukahlukene shades. It is kuhlelwe amafomu amabili ezinkulu, umbala okuyinto ziyahlukahluka kusuka ophuzi kuya konsundu kanye nabantu abamnyama. Eumelanin - ifomu melanin unikeza isikhumba umbala onsundu. Eyesibili ifomu melanin - pheomelanin, okuyinto iba nsundu ngokubomvu. Ngenxa abantu pheomelanin babe freckles noma amalangabi ngezinwele ezibomvu.
Umthelela melanin the human
Wonke umuntu kule planethi has cishe inani elifanayo labesilisa melanocytes. Leli qiniso kufakazela ukuthi bonke abantu emhlabeni, kungakhathaliseki ukuthi abelungu elinsundu noma abesifazane abamnyama isikhumba efanayo. Umbuzo in the zamagama zisifake melanin ngabanye kanye ezinye izici zangaphandle. Ngaphansi kwethonya emisebeni ultraviolet zesikhumba komuntu kuthoma ukukhiqiza melanin ngaphezulu. Lokhu kusiza ekunqandeni ukulimala kwe-DNA esikhumbeni indoda.
Ukwehluleka Uhlelo
Kodwa ngeshwa, e imithetho, kunokuningi okungakhulunywanga ngakho. Namuhla singaba ukubona isifo ezingavamile - albino. It libhekene ukuntuleka kwe-melanin e kwamangqamuzana esikhumba. Le nqubo ibizwa ebonwe kokubili ezilwaneni. Sajabulela ubukele izilwane ezimhlophe, isibonelo, ungabona ingonyama omhlophe , noma omangalisayo peacock ezimhlophe, kodwa uma kwenzeka umuntu, ngempela yinto embi kakhulu. Umuntu akakwazi ukuba isikhathi eside elangeni, isikhumba sakhe burns kweso. Umzimba uhlushwa ukuchayeka ezinzima.
Izakhamuzi abanesikhumba esimhlophe planethi
Kuvele Eqinisweni ezithakazelisayo wukuthi abameleli abelungu bakha 40% wayo yonke lwesintu. Njengoba sishilo, kuyinto umbala zofuzo ukukhanya isikhumba womuntu kubangelwa umsebenzi melanin kumaseli. Uma sicabanga ukuthi sahlala abantu iplanethi yayingagwegwesi oluthile izici ebusweni nangokuzwa umbala dermis ke ngokuhamba kwesikhathi inyumbazana ngenxa iqembu zaholela ekwakhekeni of uhlanga abanesikhumba esimhlophe. Kwenqwaba balaba bantu bahlala e-Europe, Asia naseNyakatho Afrika.
Umbala kwesikhumba womuntu, njengoba sekushiwo, kubuye sincike iziphi izici zangaphandle. Ngokwesibonelo, e-Northern Europe, abantu babe dermis alula kakhulu kunomoya Asians. Imisebe yelanga mancane abakhuthele enyakatho, ngakho abantu emhlophe kulula ukuthola umzimba udinga kavithamini D. Nakuba kufanele kuphawulwe ukuthi kukhona abantu enyakatho abanale isikhumba ngokwanele amnyama. Ngokusho imibono yososayensi, futhi kuncike ukudla.
Ngokuthakazelisayo, abantu fair isikhumba melanin ezingqimbeni engenhla epidermis elikhona amakhophi olulodwa. umbala Eye kubuye sincike kulokho ungqimba iris itholakala semali melanin. Uma lokhu ungqimba wokuqala, amehlo kuyoba ansundu kakhulu, njalo uma izingqimba ezine noma ezinhlanu, ukuthi, ngokufanele, blue noma oluhlaza.
abantu abanebala elinsundu
Labantu main kokuba amnyama, abahlala eMelika Ephakathi naseNingizimu Afrika. Abantu kule ndawo zezulu angaphansi okukhulu elangeni. Kodwa ukuchayeka emisebeni ultraviolet emzimbeni womuntu kubangela i-melanin zamagama okuyinto has a function zokuzivikela. Waba yini umphumela wesibindi ukuchayeka njalo uye elangeni uphinde waba isikhumba omnyama.
Isici ehlukile ezingeni isakhi sofuzo kubantu abanesikhumba abamnyama ukuthi amaseli wabo ukukhiqiza melanin inqwaba. Ngaphandle kwalokho, njengoba abacwaningi bathola, ungqimba engenhla epidermis abantu abanjalo ihlanganisa ngokuphelele sombala isikhumba. Leli qiniso unika ibala layo kusukela brown ukuze cishe abamnyama.
Futhi ekugcineni,
Ngalesi sikhathi, isayensi wacasulwa Iqiniso lokuthi umuntu ibala - kuwumphumela lithathelwe iqembu elithile labantu ukuba ukushuba emisebeni yelanga endaweni yokuhlala yabo. Melanin kulokhu inikeza imisebenzi isivikelo emisebeni ultraviolet okuvela elangeni, ngokungabi bikho isikhumba sakhe esasiyoba dryahlela ngokushesha okukhulu. Ngaphezu ukuguga, it kwandisa kungenzeka umdlavuza wesikhumba oyingozi.
Similar articles
Trending Now