CAS PS 241 Lecture Notes - Lecture 2: Fallopian Tube, Prenatal Development, Fetus
14 Dec 2017
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January 26th 2017
Developmental Psychology — Lecture 2
The most eventful period in development is the prenatal period, the 9 months before birth.
There is a lot of misinterpretation about pregnancy in media.
Prenatal development, things to keep in mind:
-The timing is crucial
-the sequence of events is crucial
Fertilization: possible about 14h day of menstrual cycle as ovum matures and is released into
the fallopian tubes. The nuclei of the sperm and the egg diffuse creating a new cell: the zygote.
There are three stages of fetal development:
1. germinal period (week 0-2) from conception until the developing organism attaches to the
uterine wall 8 to 14 days later. after for days from when the sperm enters the ovary, the cells
start dividing into three layers. There is some sort of signal from the zygote to the uterus for
protection.
1. cleavage — zygot transforms into blastocyst.
2. embryonic period (week 3-8) from moment of uterine attachment to end of when all major
organs have taken primitive shape.
3. fetal period (week 9-38) when bones begin to harden until birth. Primitive organs develop to
the point that fetus could exist independently.
30% pregnancies are over before the first three months — often times, women just don't know
that they are pregnant.
Getting pregnant is not as easy as some may think (7-10 days window).
Embryonic period:
Timing a sequence of events is extremely crucial. The development of nervous system happens
on the 5th week. In fact, even though the embryo is only 1.5 inches long it has specialized cells
for neural activity. By 8 weeks there is enough specialization that there is already some
organized movement (if you shine light on a woman’s belly, the embryo will be seen moving).
There is the migration of unspecialized cells into layers:
1. Endoderm, which forms the digestive system and lungs
2. Mesoderm, which forms muscles, bones, circulatory system
3. Ectoderm, which forms hair, skin, nervous system
The embryo during this period (first 8 week period) is vulnerable to disruption by environmental
factors.
Fetal period:
Women start showing.
It is the period of refinement in which baby grows in size. Finishing touches to biological
systems laid down in embryonic period. !
The fetus is less prone to environmental damage (the pregnancy is robust).
Women will experience the quickening: by the fourth month, the mother can feel the movement
of the fetus (often times, the movements start at night, when the mother is lying down).
By six moths, the fetus is active and responsive and there will also be heart rate changes. At
this point too there is viability.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The most eventful period in development is the prenatal period, the 9 months before birth. There is a lot of misinterpretation about pregnancy in media. Fertilization: possible about 14h day of menstrual cycle as ovum matures and is released into the fallopian tubes. The nuclei of the sperm and the egg diffuse creating a new cell: the zygote. There is some sort of signal from the zygote to the uterus for protection: cleavage zygot transforms into blastocyst, embryonic period (week 3-8) from moment of uterine attachment to end of when all major. 3. organs have taken primitive shape. fetal period (week 9-38) when bones begin to harden until birth. Primitive organs develop to the point that fetus could exist independently. 30% pregnancies are over before the rst three months often times, women just don"t know that they are pregnant. Getting pregnant is not as easy as some may think (7-10 days window). Timing a sequence of events is extremely crucial.
