Prenatal Development, Birth, and the Newborn Flashcards
What are the 3 periods a fertilized egg goes through before becoming an infant?
- Zygote
- Embryo
- Fetus
What happens during prenatal development?
Many changes are undergone that turn a fertilized egg into a human
What is a zygote?
A fertilized egg
How long does the period of the zygote last?
About 2 weeks
How does the period of the zygote end?
When the zygote implants itself in the wall of the uterus
How are fraternal twins created?
When the zygote splits itself in two and two eggs are released at the same time and fertilized by different sperm cells
After four days, the zygote is made up of 100 cells resembling a ball called what?
A blastocyst
After 1 week after conception, the stage where the blastocyst burrows into the uterine wall and connects with blood vessels is called what?
The implantation stage
Where in the blastocyst is the germ disc that eventually develops a baby?
Near the centre
What is an embryo?
A zygote completely embedded into the uterine wall
From what weeks of pregnancy does the period of the embryo take place?
Weeks 3-8
What are the 3 layers in the embryo and what do they form?
- Ectoderm (outer layer) - hair, skin, nervous system
- Mesoderm (middle layer) - muscles, bones, circulatory system
- Endoderm (inner layer) - digestive system, lungs
Where does the embryo rest and what is it filled in?
Rests in an amniotic sac, filled with amniotic fluid that cushions and maintains temperature
The embryo is linked to the mother via what two structures?
- Umbilical cord - houses blood vessels that join embryo to the placenta
- Villi - where blood vessels run through
From what week does the period of the fetus begin?
Week 9
