Chapter 4 - Prenatal Development Flashcards
How long are each trimester?
about 4 months
When can you tell someone is pregnant?
around month 5
most families wait to announce until second trimester since chances of random abortion are much lower
What trimester has morning sickness?
first
What is the germinal period? (period of the zygote)
from conception to implantation of the uterine wall
first 2 weeks
going through mass cell division to form blastocyst
- mitosis and meiosis
What is the period of the embryo?
week 3-8
zygote begins to take form of human
once implanted, begin to develop support structures
- amnion, chorion, placenta, umbilical cord
3 cell layers will form rapidly
What forms the placenta? What is its role?
the uterine wall
extremely important - how the baby gets its food and gets rid of waste
many complications around placenta
What is the amnion?
membrane around the embryo for temperature regulation and protection
filled with amniotic fluid from maternal tissue
What is the umbilical cord?
connect placenta to belly button of embryo
What is the chorion?
membrane that attaches to uterine tissues to gather nourishment for embryo
becomes placenta lining eventually
What is the indifferent gonad?
everybody develops the same gonad, Y chromosome triggers reaction to produce testes which produce testosterone
no reaction = ovaries
What are the 3 cell layers that form in the period of the embryo?
ectoderm
- NS (neural tube), skin, hair
mesoderm
- muscle, bone, circulatory system
endoderm
- digestive system, lungs, urinary tract, other vital organs
What happens if a brain fails to form?
encephaly
What are the key outcomes of the second month? (still in period of the embyro)
rudimentary formation of:
- facial features
- skeleton and limbs
brain rapidly develops
indifferent gonad appears
about 2.5cm and 7g
When is the period of the fetus?
week 9-month 9
half of first trimester plus entire 2nd and 3rd
becomes recognizable as human
What is happening in weeks 9-12?
organs rapidly develop
What is happening in weeks 13-24?
movement begins
react to stimuli
What is happening in weeks 25-38?
maturation
regular sleep cycles
- lots of sleep in last 2 weeks
assume fetal position
What are key developmental outcomes in month 3?
able to move but not felt by month
can swallow, digest, urinate
testosterone secreted by testes in male or female genitalia form
- ultrasound can determine sex