Prenatal Development

What are the three stages of intrauterine development?

pre-embryonic, embryonic, + fetal

When is the pre-embryonic development phase?

conception to 2 weeks

What happens in the pre-embryonic phase?

the zygote becomes a blastocyst, which then implants in the uterine lining at around 6-10 days after conception & becomes an embryo

When is the embryonic developmental phase?

3-8 weeks

What is the primary purpose of the embryonic phase?

development of baby’s organs

What happens at three weeks?

first heartbeat

What happens at 4 weeks?

neural tube fusion is completed

What happens at 6 weeks?

the heart finishes developing

What happens at 8 weeks?

first brain waves can be detected

When is the fetal development phase?

8 weeks to delivery

What is post-conception age?

doesn’t include the first two weeks of zygote & blastocyst development; begins after the blastocyst implants in the uterus

What is gestational age?

includes the first two weeks of the pre-embryonic stage, before the blastocyst enters the uterus

How long is each trimester?

13 weeks

What is the purpose of the yolk sac?

it transfers maternal nutrients and oxygen to the embryo & supports the embryo during placenta formation

What happens to the yolk sac after placental development?

it is absorbed into the embryo at around 5-6 weeks

Which side of the placenta attaches to the uterus?

the red, meaty side

Which side of the placenta is closest to baby?

the smooth, translucent side w/ the layers of the amniotic sac

How does the placenta attach to the uterus?

w/ finger-like projections called chorionic villi

What are the three primary functions of the placenta?

circulation, protection, + hormone production

What does the placenta protect baby from?

most drugs & attack from mom’s immune system

Which acronym can you use to remember the 5 hormones produced by the placenta?

H-human

E-embryos

R-require

P-positive

H-hormones

Which hormones are produced by the placenta?

HCG, HPL, estrogen, progesterone, + relaxin

What is the purpose of human chorionic gonadotropin (HCG)?

it helps establish + maintain pregnancy

What is the purpose of human placental lactogen (HPL)?

it maintains fetal growth + helps develop the mammary glands

What is the purpose of estrogen in pregnancy?

it stimulates uterine growth + helps w/ blood flow

What is the purpose of progesterone in pregnancy?

it maintains the endrometrium lining + relaxes smooth muscle

What is the purpose of relaxin?

it relaxes the joints during pregnancy

What produces these hormones before the placenta forms?

the corpus luteum

How wide is the umbilical cord?

2cm

What is the purpose of the umbilical cord?

it allows blood to travel between mom and baby

How many arteries are located in the umbilical cord?

two

What do the umbilical arteries carry and where?

deoxygenated blood; to mom

How many veins are located in the umbilical cord?

one

What does the umbilical vein carry and where?

oxygenated blood; to baby

What is wharton’s jelly?

a lining in the umbilical cord to help cushion + protect the blood vessels (this prevents vessel collapse)

What are the two layers of the amniotic sac?

chorion + amnion

What is the chorion?

the thicker, outer membrane, located closest to the uterine wall

What is the purpose of the chorion?

it provides mechanical support for the fetus

What is the amnion?

the inner membrane, located closest to the fetus

What is the purpose of the amnion?

it helps protect the fetus by holding the amniotic fluid and helps regulate the pregnancy

What makes up the amniotic fluid?

water, electrolytes, hormones, + cells

What is the purpose of amniotic fluid?

it cushions the baby from trauma, regulates temperature, contains antibodies, + stores waste