PSYB20H3 Lecture Notes - Lecture 3: Amniotic Sac, Miscarriage, Fetus
Document Summary
Day 1 is counted from last period. Parental is commonly counted from week three and onwards. All body parts differentiated by 8 weeks. Head brain and eyes develop earliest and disproportionally. Limbs later ones to develop since distal from body. Stem cells have potential to become any cell in body. They are unspecialized and they can renew themselves through cell division. Under certain condition they can be introduced to become anything you want it to become (make it become neuron in lab for example). In humans stem cells will become 350 different types of cells. Cell death is so fetus could get better developed. Cell within plates of fingers to die so our fingers could be differentiated and not have webbed hands. Only 20% chance to properly line to get pregnant. Heart starts to beat in about 4 weeks and circulate blood. Amniotic sac for protection and for free movement to strengthen its muscles.
