Download 1st Trimester Guided Notes

FIRST TRIMESTER GUIDED NOTES
WEEK 1
_______________hours after fertilization begins, pregnancy can be confirmed by
detecting a hormone called “__________________in the mother’s blood (The test for this
hormone, however, is not widely available). This substance helps prevent the mother’s
immune system from rejecting the soon-to-be-implanted embryo and allows pregnancy
to proceed.
_______________ is the process whereby the early embryo embeds into the inner wall of
the mother’s uterus. Implantation begins about 6 days after fertilization and is complete
by about 12 days.
Embryo begins receiving nourishment directly from the cells lining the mother’s
______________
WEEK 1- 2
Approximately 8 days after fertilization, cells from the growing embryo begin producing
a hormone called_______________________________. This hormone is present in a pregnant
woman’s blood and urine almost immediately and is the substance detected by most
pregnancy tests.
Nutrients, oxygen, vitamins, and water in the mother’s blood stream pass through the
_______________ and ________________to the embryo; while carbon dioxide and other
waste flows back to the mother. The placenta also produces hormones and maintains
fetal temperature above the mother’s temperature
A twisting cord of blood vessels, called the___________________, connects the embryo to
the placenta.
WEEK 2-3
Stem cells have divided and differentiated into 3 different germ layers called
_________________
________________, & ___________________. Each gives rise to major
components of specific body structures and organs.
**List 4 parts that will derive from the Ectoderm
**List 4 parts that will derive from the Endoderm
**List 4 parts the will derive from the Mesoderm
3 - 4 WEEKS
Only 3 weeks and 1 day after fertilization – the________________________.
weeks, the heart typically beats between 105 and 121 times per minute.
Upper and lower ________________ appear by four weeks
By 4
4- 5 WEEKS
At this point, the embryo’s skin is only one cell thick. This makes the
skin_______________, allowing us to see internal organs during early development.
5- 6 WEEKS
Embryo begins to ____________
6-7 WEEKS
The embryo has ____________ by 6 weeks, 2 days!
Hiccups begin
OLDEST BONES IN YOUR BODY=Bone formation begins between 6 and 7 weeks, starting
with the clavicle, or collar bone, and the upper and lower jaw. This process is
called________________.
By 7 weeks, the ovaries appear in the female embryo. In the male embryo, a gene on the
Y-chromosome produces a substance causing the testes to begin to differentiate.
7-8 WEEK
The embryo also kicks, and will jump if startled.
By 8 weeks the _____________ is highly developed
8-9 WEEKS
Thumb sucking begins and the fetus may swallow ____________
9-10 WEEKS
By this point, ossification is underway in most bones.
Fingers and toes, nails begin to emerge, as do _________________.
10-11 WEEKS
The nose and lips are completely formed.
Though gender is determined at fertilization, _______________now distinguish male from
female.
11-12 WEEKS
No diapers in the womb! = the fetus _____________directly into the amniotic fluid. (But
remember, the umbilical cord is also removing waste.)