HRR: female repro physiology III Flashcards
Where does fertilization typically occur?
In the ampulla
At the point of fertilization, what is the cervical mucus typically like?
Very thin via estrogen mediation; this makes it so the sperm can effectively travel!
When does a fertilized embryo enter the uterine cavity?
3-4 days after fertilization
What does progesterone inhibit during pregnancy?
Uterine contraction, prostaglandin synthesis, oxytocin receptors, estrogen receptor synthesis, immune responses
What does progesterone do to uterine contractions?
Inhibits them! Keeps us from contracting a fertilized embryo out of the uterus
What is the decidua?
A specialized group of endometrial cells that provides nutrients to the embryo during pregnancy
How long into pregnancy does the corpus luteum function?
About 6-8 weeks
What becomes the hormone warehouse during pregnancy?
The placenta. Takes over for the corpus luteum around week 8
___ is essential for implantation.
Progesterone; no implantation without it!
Describe the course of hCG through pregnancy.
It peaks around 8-10 weeks, and slowly declines after that
What regulates hCG synthesis?
Placental GnRH can increase synthesis. Other than that we don’t really know.
Describe the course of progesterone through pregnancy.
It continues to go up throughout, and in huge quantities! Without progesterone, uterine contractions are not inhibited, and we increase the likelihood of miscarriage
Describe the course of estrogen through pregnancy.
It continues to go up throughout pregnancy, but not anywhere near the same quantity as progesterone.
Describe the beta subunit of hCG.
The beta subunit is very similar to LH, so it binds to hLH-hCG receptor. It stimulates the corpus luteum, has a 36-hour half-life, and has a super high carbohydrate content
Describe placental lactogen (hPL or hCS).
Its synthesis correlates with the developing placenta/embryo. It increases maternal lipolysis, blood glucose, and impact breast tissue and mammary growth.
Describe glucose/insulin levels in a normal pregnancy.
Mild fasting hypoglycemia, postprandial hyperglycemia, and hyperinsulinemia. This is because a normal pregnant woman is a little insulin resistant to allow slightly higher glucose levels to allow it to be transferred to the fetus for energy
How does hPL impact glucose levels, and why?
Sustains postprandial hyperglycemia to allow for a supply of glucose to the developing fetus
Why is maternal lipolysis increased in pregnancy?
They use this as an energy source to divert more glucose to the developing fetus
Describe the course of hPL (hCS) through pregnancy.
It increases throughout pregnancy as the placenta and embryo continue to grow
How do we make androgens in the placenta?
We don’t; the placenta does not have the 17a hydroxylase complex, so androgens cannot be made
How do we make estrogen in the placenta?
Androgens from other maternal and fetal tissues are transferred to the placenta, where aromatase can form estrone and estradiol
Most estrone and estradiol formed in the placenta are derived from…
DHEAs from fetal adrenal glands
95% of estriol is made from…
DHEAS from fetal adrenal glands
Describe the formation of estriol.
- Fetal adrenals form DHEAS
- DHEAS moves to the fetal liver and a hydroxy is added
- 16-OH DHEAS moves to the placenta, where the sulfate is ripped off and aromatase forms estriol
What does estriol do to uteroplacental blood flow?
Increases it!
What can the levels of estriol tell us?
The viability and well-being of the fetus!! This is because its production is dependent on the fetal adrenal glands and liver
How does the placenta get cholesterol for steroid production?
Via maternal uptake of cholesterol; the placenta cannot synthesize enough on its own
How does estrogen impact cholesterol?
Increases placental LDL receptors and cholesterol uptake
___ promotes uterine contraction, while ___ prevents contraction.
Estrogen, progesterone
What is the role of CRH in delivery of a fetus?
It increases myometrial contractility! Levels remain pretty low up until it is time to get ready to deliver
What does estrogen promote around the time of delivery?
Increased oxytocin receptors, gap junctions, prostaglandins
