Learn about prenatal and newborn development
a) from conception to birth is about nine months
b) a single fertilized egg cell (carries all genetic info needed) will turn into a baby
c) during this time many positive/negative things can affect the child
12.1- trace physical development from conception through birth and identify influences on prenatal development
1) Fertilization, the Zygote, and Twinning
a) egg (aka ovum) and sperm meet in process of fertilization
b) resulting cell has 46 chromosomes and is called a zygote
c) zygote divides (1,2,4,8,...) & each new cell also has 46 chromosomes b/c DNA molecules duplicate themselves before each division (called mitosis)
d) normally produces baby, sometimes messes up and produces 2+
e) 2 main types of twins: monozygotic- identical; both come from one fertilized egg. dizygotic- fraternal; two fertilized eggs (more likely in older women or those taking fertility drugs.
f) very useful in Nature vs. Nurture debate research
g) mass of cells might not completely split apart: which causes conjoined twins
2) The Three Stages of Development
2.1)The Germinal Period
a) germinal period- first two weeks after fertilization, during which the zygote moves down to the uterus and begins to implant the lining
b) during the germinal period, cells begin to differentiate (developing into specialized cells to become various cells (ex. skin, heart, ect...)
c) btw- stem cells are super important
2.2) The Embryonic Period
a) embryonic period- the period from 2 to 8 weeks after fertilization, during which the major organs and structures of the organism develop.
2.3) The Fetal Period
a) fetal period- the time from about 8 weeks after conception until the birth of the child (now referred to as fetus).
12.2- Explain the role of sensitive and critical periods in development
1) Critical Periods
a) critical periods- times during which certain environmental influences can have an impact on the development of an infant
2) Prenatal Hazards: Teratogens
a) teratogen- any factor that can cause a birth defect.
b) The most common teratogen is alcohol.
c) Teratogens can cause fetal alcohol syndrome (fas), which is a series of mental and physical health defects.