PSY 230 Lecture Notes - Lecture 5: Embryonic Disc, Preterm Birth, Miscarriage
Document Summary
Prenatal development: germinal period (first two weeks) Blastocyst cell mass with two parts, placenta and nucleus: 4-5 days in, becomes the embryonic disk and trophoblast. Work to achieve implantation 8 to 14 days: about 60% do not achieve this, and do not survive this period, embryonic period (third to 8th week) Becomes a distinct embryo: trophoblast develops. Amnion water tight sac that protects and regulates the baby. Chorion surrounds the sac, and is the lining of the placenta. Placenta forms from the lining of the uterus and chorion, serves as a passage to infant for oxygen/nutrients and to get rid of waste. Umbilical cord link between embryo and placenta, contains a large vein and two arteries, 1-3 feet in length: embryonic disc. Endoderm (lower layer) becomes lungs, digestive system. Mesoderm (middle layer) comes skeletons, muscles, and cardiovascular. Ectoderm (outer layer) skin, hair, nails, nervous system. 20% are aborted spontaneously due to developmental issues (chromosome abnormalities)
