Basa reMelanin muPigment yeganda
Ganda remunhu rine mavara akasiyana-siyana, kubva pachiedza chakajeka kusvika parima. Misiyano iyi inonyanya kukonzerwa nechimwe chinhu chikuru chehupenyu: melanin, ruvara rwechisikigo runogadzirwa nemuviri. Melanin haingoiti basa rekuona ruvara rweganda chete asiwo ine mabasa akakosha ekudzivirira, kunyanya mukudzivirira ganda kubva kumhedzisiro yemwaranzi ye ultraviolet (UV). Chinyorwa chino chinotaura nezve melanin, kuti inogadzirwa sei, mhando dzayo, zvinhu zvinopesvedzera huwandu hwe melanin, uye hukama hwayo nehutano hweganda.
Chii chinonzi melanin?
Melanin imhando yeruvara inogadzirwa nemasero akasarudzika anonzi melanocytes, anowanikwa muchikamu chepasi cheganda (chikamu chekunze cheganda). Melanin inowanikwawo mubvudzi nemaziso, nokudaro ichipesvedzera ruvara rwazvo. Panyaya yeganda, melanin inoshanda se "chipingamupinyi chezvisikwa," sezvo ichitora uye ichiparadzira simba kubva kumwaranzi yeUV.
Huwandu hwema melanocytes muvanhu hunowanzo fanana pakati pevanhu vemarudzi akasiyana kana mapoka emadzinza. Chinosiyanisa ruvara rweganda hachisi kunyanya huwandu hwemasero, asi mashandiro ema melanocytes uye huwandu nerudzi rwe melanin inogadzirwa, kusanganisira kuti pigment inogoverwa sei kumasero eganda akakomberedza.
Maitiro ekugadzirwa kwemelanin (melanogenesis)
Kugadzirwa kwemelanin kunozivikanwa se melanogenesis. Maitiro aya anoitika muzvikamu zvidiki zvema melanocytes zvinonzi melanosomes. Ma melanosomes anogona kufungidzirwa se "mafekitori" uko melanin inogadzirwa yozoiswa mumapaketi isati yaendeswa kune mamwe masero eganda.
Zvichitaurwa zviri nyore, kuumbwa kwemelanin kunotanga neamino acid tyrosine. Enzyme huru mukuita uku ityrosinase. Tyrosinase inobatsira kushandura tyrosine kuita macompounds ari pakati nepakati (akadai sedopa nedopaquinone), ayo anobva aita maitiro akasiyana-siyana emakemikari kuti aumbe melanin.
Kana melanin yangoumbwa, melanosomes dzine pigment dzinotamiswa kubva kumelanocytes kuenda kukeratinocytes (masero eganda makuru ari mu epidermis). Mukati mekeratinocytes, melanin inoumba chimiro chakaita seambrela chakakomberedza nucleus yesero, zvichibatsira kudzivirira DNA kubva mukukuvadzwa neUV. Maitiro aya akakosha nekuti kukuvara kweDNA kunogona kuwedzera njodzi yekukwegura nguva isati yakwana uye kenza yeganda.
Mhando dze melanin uye mhedzisiro yadzo paruvara rweganda
Kune mhando dzinopfuura imwe chete dze melanin. Kazhinji, kune mhando mbiri huru dze melanin muvanhu:
1. Eumelanin
Eumelanin ine ruvara rwebrown kusvika dema. Rudzi urwu runonyanya kushanda pakunwisa mwaranzi yeUV uye runowanzoonekwa nevanhu vane ganda rakasviba. Eumelanin ine basa guru mukuva neruvara rwebvudzi dema kana dema.
2. Pheomelanin
Pheomelanin inowanzova neruvara rweyero-tsvuku. Pigment iyi inowanikwa zvakanyanya kuvanhu vane bvudzi dzvuku kana dzvuku-blonde, pamwe chete nevanhu vane ganda rakajeka. Kana ichienzaniswa ne eumelanin, pheomelanin haishande zvakanaka pakudzivirira kubva kumwaranzi yeUV uye, mune mamwe mamiriro ezvinhu, inogona kukonzera kuumbwa kwemafree radicals nyore nyore kana yaiswa pachiedza chezuva.
Kusanganiswa kwehuwandu nechiyero cheeumelanin nepheomelanin, pamwe chete nekupararira kwazvo muganda, kunoita kuti pave neruvara rwakasiyana-siyana rweganda revanhu. Nokudaro, ruvara rweganda harusi "dema kana chena," asi mhedzisiro yekusiyana kwakaoma kwemavara uye mhinduro dzemuviri.
Basa re melanin kune ganda rine hutano
Melanin inowanzo taurwa nezvayo sechinhu chinosarudza ruvara rweganda, asi basa rayo guru nderekudzivirira. Heano mamwe mabasa akakosha e melanin:
1. Dziviriro kubva kumwaranzi yeUV
Mwaranzi yeUV inogona kukanganisa DNA uye chimiro chemasero eganda. Melanin inonwisa imwe yemwaranzi iyi uye inoderedza kupinda kweUV muzvikamu zvakadzika zveganda. Nokudaro, ganda rine huwandu hwakawanda hwe eumelanin rinowanzova nenjodzi shoma yekupiswa nezuva kupfuura ganda rakareruka.
2. Inoderedza kushushikana kwe oxidative
Kusviba nezuva kunogona kuwedzera kuumbwa kwemafree radicals, ayo anokuvadza collagen, elastin, uye membrane dzemasero. Melanin inobatsira kurwisa zvimwe zvezvipingamupinyi izvi, kunyange hazvo dziviriro yayo isiri yakakwana, kunyanya kana kusviba kweUV kwakawanda kana kuti kwenguva refu.
3. Inobatsira pakuita kuti ganda rizvimbe uye kuti richembere.
Kukuvadzwa neUV kunobatsira pakukwegura nguva isati yakwana (photoaging) zvakaita semakwinya, mavanga ekukwegura, uye magadzirirwo eganda asina kunaka. Nekunwa chiedza cheUV, melanin inobatsira kuderedza mwero wekukuvadzwa uku. Zvisinei, nekukura, kupararira kwepigment kunogona kusaenzana, zvichikonzera kuwedzera kwepigmentation munzvimbo dzakadai semavanga ekukwegura.
Zvinhu zvinokanganisa huwandu hwe melanin
Huwandu hwe melanin muganda remunhu hunokonzerwa nezvinhu zvakaita semajini uye nharaunda. Zvimwe zvezvinhu zvikuru zvinosanganisira:
1. Majini
Majini anoona hwaro hweruvara rweganda nekudzora mashandiro e melanocyte, huwandu hwe melanosomes, uye rudzi rukuru rwe melanin. Nokudaro, ruvara rweganda runowanzo tevedzera maitiro ekugara nhaka mumhuri. Zvisinei, majini anoshanda ne polygenic (zvichipesvedzerwa nemajini akawanda), saka misiyano inogona kusiyana zvikuru.
2. Kupisa zuva
Kusviba neUV kunokurudzira melanocytes kuti ibudise melanin yakawanda, zvichikonzera ganda rakasviba. Maitiro aya anozivikanwa sekuti kusviba neganda, kana kuti kupiswa nezuva. Kusviba neganda inodzivirira, kwete chiratidzo chekuti "ganda rine hutano." Kusviba neUV zvakanyanya kunogona kukonzera kukuvara kwenguva refu.
3. Mahormone nemamiriro emuviri
Kuchinja kwemahormone kunogona kukanganisa ruvara rweganda. Semuenzaniso, panguva yekuzvitakura kana kushandisa mishonga yekudzivirira pamuviri ine mahormone, vamwe vanhu vanowana melasma (brownish patches) nekuda kwekuwedzera kwekushanda kwe melanocyte. Mamwe mahormone, akadai seMSH (melanocyte-stimulating hormone), anobatanidzwawo mukudzora kugadzirwa kwe melanin.
4. Kuzvimba nekukuvara kweganda
Mapundu, eczema, maronda, uye nzira dzinotsamwisa ganda zvinogona kukonzera hyperpigmentation mushure mekuzvimba (PIH), kunyanya kune vanhu vane ganda rakatsvuka kusvika dema. Kana kuzvimba kwapera, mavara matema anogona kuramba aripo nekuda kwekuwedzera kwekugadzirwa kwemelanin munzvimbo yakakanganiswa.
5. Zera
Sezvatinokura, mashandiro e melanocyte anogona kudzikira, asi kupararira kwepigment kunogona kusaenzana. Izvi zvinogona kukonzera kuoneka kwemavara matema (lentigines) munzvimbo dzine zuva dzakadai sekumeso nekumashure kwemaoko.
Matambudziko ane chekuita neMelanin
Melanin yakawandisa, shoma, kana kuti isina kugoverwa zvakaenzana inogona kukonzera matambudziko akasiyana-siyana eruvara rweganda, kusanganisira:
– Kusviba kweganda: kusviba kwenzvimbo dzeganda, dzakadai se melasma, PIH, kana mavanga anozowedzera kana munhu akanyanya kupiswa nezuva.
– Kuchinja ruvara rweganda: ruvara rweganda runonyangarika mune dzimwe nzvimbo, semuenzaniso muzvirwere zvevitiligo (kurasikirwa neruvara rweganda nekuda kwezvirwere zve autoimmune) kana pityriasis versicolor (inokonzerwa nefungus).
– Albinism: chirwere chemajini umo kugadzirwa kwe melanin kushoma kana kuti kusina, zvichikonzera ganda rakapfava, bvudzi, nemaziso uye kunzwa UV zvakanyanya.
Matambudziko aya haasi nguva dzose ane njodzi, asi mamwe anoda kurapwa nekuda kwekudzivirirwa kweUV uye kukanganisa kwepfungwa.
Kudzivirira ganda neMelanin: chii chinofanira kuitwa?
Kunyange zvazvo melanin ichidzivirira zvakasikwa, hazvirevi kuti munhu haagoni kubatwa nezuva. Mavara ese eganda ari panjodzi yekukuvadzwa neUV. Matanho akakosha aunogona kutora anosanganisira:
– Shandisa mafuta ekudzivirira zuva ane SPF yakakwana wozorazve.
– Pfeka dziviriro yemuviri yakadai sengowani nembatya dzakavharwa kana zuva richipisa.
– Deredza kupiswa nezuva zvakanyanya, kunyanya panguva yekushanya kwakanyanya.
– Rapa kuzvimba kweganda (semuenzaniso mapundu) kudzivirira mavanga ekuwedzera pigmentation.
Mhedziso
Melanin ipendi inokosha inosarudza ruvara rweganda uye inoita basa guru mukudzivirira kubva mukukuvadzwa neUV. Inogadzirwa mumelanocytes kuburikidza nemaitiro e melanogenesis, uye zvigadzirwa zvinogoverwa kune mamwe masero eganda kuchengetedza DNA. Kusiyana kwemarudzi e melanin - eumelanin ne pheomelanin - pamwe chete nezvinhu zvemajini, kuratidzwa nezuva, mahormone, kuzvimba, uye zera zvinopa mutsauko mukuchinja kwemavara. Kunzwisisa basa re melanin kunotibatsira kuziva kuti ruvara rweganda imhedzisiro yekuchinja kwakaoma kwehupenyu, uye kuti kuchengetedza ganda rine hutano kwakakosha kune wese munhu, zvisinei neruvara rweganda.
