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National Geographic Society This program is distributed in the U.S. and Canada by National Geographic and EHD. [learn more]

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The Biology of Prenatal Development




UKUFUNDA NGOKWENZEKAYO NGAPHAMBI KOKUZALA

.isiZulu [Zulu]


 
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Chapter 1   Introduction

Uhlelo olubabazekayo lwe-zygote eneseli elilodwa eba wumuntu onamaseli angu 100-trillion mhlawumbe yisehlo esigqame kunazo zonke kwimvelo.

Abaphenyi sebeyazi ukuthi imisebenzi eminingi evamile yomzimba womuntu omdala isunguleka esesesiswini - kusekude azalwe.

Ukukhula ngaphambi kokuzalwa sekuthathwa njengesikhathi sokulungiselela okuthi ngaso umuntu okhulayo athole izakhiwo eziningi, enze namakhono amaningi, okudingeka ekuphileni esezelwe.

Chapter 2   Terminology

Ukukhulelwa kubantu kuba cishe wu 38 amaviki kusukela ekuhlanganeni kwembewu neqanda, kuye ekuzalweni.

Ngamaviki okuqala awu 8 emva kokukhulelwa, umuntu okhulayo kuthiwa wumbungu, okuwukuthi "kukhula ngaphakathi." Le sikhathi, okuthiwa esombungu, sigqame ngokwakheka kweningi lezinhlelo ezisemqoka zomzimba.

Ukusuka emva kwamaviki awu 8 kuya ekubeletheni, "umuntu okhulayo kuthiwa yi-fetus," okuwukuthi "okungakazalwa." Ngale sikhathi, okuthiwa esokungakazalwa, umzimba uyakhula nezinhlelo zawo ziqale ukusebenza.

Bonke ubudala bombungu ne-fetus kulo luhlelo kusho isikhathi kusukela ekukhulelweni.

The Embryonic Period (The First 8 Weeks)

Embryonic Development: The First 4 Weeks

Chapter 3   Fertilization

Ngokwemithetho yempilo, "ukukhula komuntu kuqala ekukhulelweni," uma owesilisa nowesifazane emunye efaka 23 wama-chromosomes abo ngokuhlangana kwamaseli abo enzalo.

Iseli yenzalo yowesimame kuthiwa yi"qanda" kodwa igama eliyilo yi-oocyte.

Ngokunjalo, iseli yenzalo yowesilisa kuthiwa yi"mbewu" kodwa kungcono uma kuthiwa yi-spermatozoon.

Emva kokukhishwa kweqanda esizalweni sowesimame ngohlelo okuthiwa yi-ovulation, iqanda nembewu kuyahlangana kwelinye lamashubhu esibeletho, avame ukubizwa ngama-Fallopian tubes.

La mashubhu ahlanganisa isizalo sowesimame nesibeletho sakhe.

Umbungu owumphumela kuthiwa yi-zygote, okuwukuthi "kuhlangene."

Chapter 4   DNA, Cell Division, and Early Pregnancy Factor (EPF)

Ama-chromosomes e-zygote awu 46 amele ingxenye yokuqala yesifanekiso sofuzo somuntu omusha. Le sakhiwo sihlala kumamolikuli athothene okuthiwa yi-DNA. Inemiyalelo yokukhula komzimba wonke.

Amamolikuli e-DNA anjengesikhwelo esisontekile okwaziwa njenge-double helix. Amaqophelo esikhwelo enziwe ngamamolikuli angamabili, okuthiwa yi-guanine, cytosine, adenine, ne-thymine.

I-guanine ihambisana kuphela ne-cytosine, i-adenine ihambisane ne-thymine. Iseli ngalinye lomuntu cishe libe no 3 billion wala mapheya ayiziqu.

I-DNA yeseli elilodwa inolwazi oluningi kangangoba uma lungahle lubhalwe ngamagama, ukuhlela igama lokuqala lesiqu ngasinye kungadinga amakhasi angaphezu kuka 1.5 million!

Uma ilandelaniswa, iDNA kwiseli lomuntu elilodwa ikaleka ibewu 3 1/3 amafidi noma 1 imitha.

Uma singayiqaqa yonke iDNA ekumaseli omuntu angu 100 trillion, ingaba ngaphezu kwamamayela angu 63 billion. Le libanga lifika elangeni libuye izikhathi eziwu 340.

Cishe emahoreni awu 24 kuyaku 30 emva kokukhulelwa, i-zygote iqeda ukuhlukaniseka kwamaseli kokuqala. Ngohlelo lwe-mitosis, iseli lihlukaniseka kabili, amabili abe mane, njalonjalo.

Emva kuka 24 kuyaku 48 amahora ukukhulelwa kuqalile, kungaqinisekiswa ngokuthola ihomoni okuthiwa "wuphawu lokuqala " egazini likamama.

Chapter 5   Early Stages (Morula and Blastocyst) and Stem Cells

Ngosuku luka 3 kuyaku 4 emva kokukhulelwa, amaseli andayo ombungu aba sandilinga bese umbungu kuthiwa yi-morula.

Ngosuku luka 4 noma 5, kwakheka umgodi kule libhola lamaseli bese umbungu kuthiwa yi-blastocyst.

Amaseli ngaphakathi kwi-blastocyst kuthiwa yinqwaba yamaseli angaphakathi kanti akha ikhanda, umzimba, nezinye izakhiwo ezisemqoka kumuntu okhulayo.

Amaseli angaphakathi kule nqwaba yamaseli kuthiwa ama-embryonic stem cells ngoba akwazi ukwakha inhlobo ngayinye yamaseli kwezingaphezu kuka 200 asemzimbeni womuntu.

Chapter 6   1 to 1½ Weeks: Implantation and Human Chorionic Gonadotropin (hCG)

Emva kokwehla ngeshubhu lesibeletho, umbungu wokuqala uzishutheka odongeni olungaphakathi lwesibeletho sikamama. Lo luhlelo, okuthiwa wukuzihloma, luqala emva kuka 6 izinsuku luphele emva kuka 10 kuyaku 12 izinsuku emva kokukhulelwa.

Amaseli ombungu okhulayo aqala ukukhiqiza ihomoni okuthiwa yi-human chorionic gonadotropin, noma hCG, etholwa yiningi lokuhlolela ukukhulelwa.

I-HCG itshela amahomoni owesimame ukuthi akuyekise ukuya esikhathini okuvamile, okuvumela ukukhulelwa kuqhubeke.

Chapter 7   The Placenta and Umbilical Cord

Emva kokuzihloma, amaseli azungeze i-blastocyst akha ingxenye yalokho okuthiwa yi-placenta, ewukuxhumana phakathi kohlelo lukamama nolombungu lokugeleza kwegazi.

I-placenta ihambisa i-oksijini, izakhamzimba, amahomoni, nemithi kukamama embungwini okhulayo; isusa wonke udoti; bese ivimba ukuxubana kwegazi likamama nelombungu nele-fetus.

I-placenta ibuye Ikhiqize amahomoni ibuye igcine izinga lokushisa lomzimba wombungu libe ngaphezudlwana kwelikamama.

I-placenta ixhumana nomuntu okhulayo ngemithambo yenkaba.

Amakhono enkaba okweseka impilo e-placenta alingana nalawo amagumbi abagula kakhulu ezibhedlela zesimanje.

Chapter 8   Nutrition and Protection

Ngeviki 1, amaseli enqwaba yamaseli engaphakathi akha izingqimba ezimbili okuthiwa yi-hypoblast ne-epiblast.

I-hypoblast yakha i-yolk sac (isikhupahshi), okungesinye sezakhiwo okuthi ngaso umama aphakele izakhamzimba kumbungu wasekuqaleni.

Amaseli aphuma kwi-epiblast akha ijwabu okuthiwa yi-amnion, ngaphakathi embungwini kamuva kwi-fetus liyakhula kuze kube wukuzalwa.

Chapter 9   2 to 4 Weeks: Germ Layers and Organ Formation

Cishe ngo 2 1/2 amaviki, i-epiblast seyakhe 3 amathishu ayisipesheli, noma izingqimba zamagciwane, okuthiwa yi-ectoderm, endoderm, ne-mesoderm.

I-ectoderm yakha izakhiwo eziningi kubandakanya ubucopho, umgogodla, imizwa, isikhumba, izinzipho, nezinwele.

I-endoderm ikhiqiza untwentwesi lomgudu wokuphefumula nolomgudu wokugaywa kokudla, bese yenza izingxenye zezitho ezisemqoka njengesibindi namanyikwe.

I-mesoderm yakha inhliziyo, izinso, amathambo, uqwanga, imisipha, amaseli egazi, nezinye izakhiwo.

Emva kwamaviki awu 3 ubuchopho buhlukaniseka ezingxenyeni zokuqala eziwu 3 okuthiwa wubuchopho baphambili, ubuchopho obuphakathi, nobuchopho obungemuva.

Ukukhula kwemigudu yokuphefumula nowokugaywa kokudla nako kuyaqhubeka.

Khathi amaseli okuqala egazi evela kwi-yolk sac, kwakheka imithambo yegazi kuwowonke umbungu, bese kuvela inhliziyo esashubhu.

Cishe ngokuphazima kweso, inhliziyo ekhula ngamandla iyazisonga ngenkathi amakamelo ehlukene eqala ukwakheka.

Inhliziyo iqala ukushaya kumaviki awu 3 nosuku emva kokukhulelwa.

Umgudu wegazi wumgudu womzimba wokuqala, noma iqembu lezitho ezihlobene, oveza isimo sokusebenza.

Chapter 10   3 to 4 Weeks: The Folding of the Embryo

Phakathi kuka 3 no 4 wamaviki, isakhiwo somzimba siyavela ngesikhathi ubuchopho, umgogodla, nenhliziyo kombungu sekubonakala kalula eceleni kwe-yolk sac.

Ukukhula ngamandla kudala ukusongeka kombungu owendlalekile. Lo luhlelo luhlanganisa ingxenye ye-yolk sac ontwentwesini lomgudu wokugaya ukudla bese lwakha imigodi yesifuba nowesisu yomuntu okhulayo.

Embryonic Development: 4 to 6 Weeks

Chapter 11   4 Weeks: Amniotic Fluid

Kumaviki awu 4 i-amnion ecacile izungeza umbungu esakeni eligcwele uketshezi. Lo luketshezi olungenamagciwane, okuthiwa yi-amniotic fluid, luvikela umbungu ekulimaleni.

Chapter 12   The Heart in Action

Inhliziyo ishaya izikhathi eziwu 113 ngomzuzu.

Qaphela indlela inhliziyo eguqula ngayo umbala uma igazi lingena noma liphuma emagumbini ayo uma ishaya.

Inhliziyo izoshaya cishe izikhathi eziwu 54 million ngaphambi kokuzalwa nangaphezu kuka 3.2 billion esikhathini esiyiminyaka yempilo engu 80.

Chapter 13   Brain Growth

Ukukhula ngamandla kobuchopho kuvezwa wukushintsha kokubukeka kobuchopho obuphambili, ubuchopho obuphakathi, nobuchopho obungemuva.

Chapter 14   Limb Buds

Kuqala ukukhula kwezingalo nemilenze ngokuvela kwamahlumela emavikini awu 4.

Kule nkathi isikhumba sikhanya ngale ngoba siwugqinsi ngeseli kuphela.

Uma lwanda ugqinsi lwesikhumba, ngeke sisabonakala ngale, okushukuthi sizokwazi ukubona izitho zangaphakathi zikhula cishe enye inyanga.


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