PSYCH 1101 Chapter 11: Development
22 Nov 2016
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Fertilized egg that contains chromosomes from both an egg and a sperm. 23 chromosomes in each sperm and in each egg. 23rd: sex chromosomes: xy: germinal stage. Zygote travels down fallopian tube and implants in wall of uterus. Name for zygote that successfully implants itself in uterine wall: embryonic stage. Period that lasts from 2nd week until about 8th week. 1 inch long: embryo has beating heart and other body parts (arms/legs) Xy chromosome embryos begin producing testosterone rep. organs: fetus. Embryo @ 9 weeks: fetal stage. Period that lasts from 9th week until birth. Brain cell division complete by 24 weeks. Myelination: formation of fatty sheet around axons: continues throughout adulthood, rapid and complex growth. Newborn human brain is only 25% of adult size. Will need to adapt, shaped by unique social and physical. Prenatal environment environment why we are adaptable: placenta. Organ that physically links bloodstreams of mother and the embryo or fetus.
