PSYCH211 Chapter Notes - Chapter 4: Prenatal Development, Umbilical Cord, Prenatal Care
2 Feb 2016
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Prenatal development begins after sperm fertilizes egg. Prenatal development fertilized egg to human being. Pregnancy duration from the start of last menstrual cycle ( 2 weeks before. 38 weeks are divided into 3 stages: period of the zygote, period of the embryo conception) and period of the fetus. Period of the zygote (weeks 1-2) zygote grows rapidly through cell division zygote travels down fallopian tube towards the uterus and undergoes first cell division cell division occurs ever 12 hours. Begins with fertilization and lasts 2 weeks. Ends when fertilized egg called zygote implants itself in the wall of the uterus. By end of first week zygote reaches uterus. Germ disc - center of zygote becomes the baby. Other cells become structures that support the baby. Period of the embryo (weeks 3-8) ( digestive and lungs) At beg, 3 layers form in the embryo. Ectoderm, mesoderm ( muscles, bone and circulatory system), and endoderm. 3 week embryo is 2 mm long.
