PSYB32H3 Chapter Notes - Chapter 3: Spina Bifida, Amniotic Sac, Umbilical Cord
Document Summary
Once the zygote is implanted; from the 3rd week of pregnancy to the 8th week. Period of rapid growth; recognizable as a human; increases 2 million% in size. The amniotic sac, placenta and umbilical cord develops that protects the baby. The placenta is semi permeable; separates the mother"s and child"s blood but something can be passed on like nutrients and oxygen to the baby and wastes from the baby to be excreted. The inner mass differentiates in three layers: ectoderm: hair, nails, teeth, skin, mesoderm: muscles, skeleton, circulatory and excretory systems, endoderm: gastrointestinal tract, trachea and bronchia, lungs, liver. The rapid change makes the embryo susceptible as during the neural folds, if something happens that prevents them from closing completely, the child will develop spina bifida. The 2 prenatal development principle: cephalocaudal: head downwards, proximal distal: centre outwards. By the end of 8 weeks, face, fingers, genitals are present. Beginning of the 3rd month to delivery.
