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62 Cards in this Set

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  • Back
When does most fertilization occur after ovulation?
Within about a day
Where does fertilization occur?
Within the uterine tube
What happens after fertilization at day 1?
Cell division begins in the zygote and it makes its way down the greasy, noncontractile (prog) fallopian tube.
Why do you want the first events to occur in the fallopian tube?
So that the blastocyst can get ready to implant in the uterine wall.
What day does the blastocyst reach the uterus? When does it implant?
Arrival day: 4-5
Implant day: 5-7
which part of the blastocyst invades the endometrium?
Trophoblast cells
Why are the trophoblast cells important?
They produce hCG
What is required in order for hCG to be measured in the mom?
It has to CONTACT the uterine wall!
How soon after the LH peak does hCG rescue the corpus luteum?
About 10 days after
(2-3 days after implantation)
What is the important effect of rescuing the corpus luteum?
Estrogen/progesterone don't decrease! Pregnancy can ensue!
What does the presence of Estrogen and Progesterone prevent?
The next LH surge - you don't WANT another set of 6-8 follicles to develop if you're pregnant.
But doesn't Estrogen CAUSE the LH surge by its positive feedback?
Yes, but that's estrogen being produced by the dominant follicle, not from the corpus luteum.
So what is THE gonadotropin during the 1st trimester of pregnancy that is absolutely necessary?
hCG - it rescues the corpus luteum and prevents the next menstrual cycle/ovulation.
SWhat is the corpus luteum basically?
A steroid producing factory - makes Progesterone (and estrogen)
What are the 2 main effects of progesterone from the CL?
1. Suppression of FSH/LH from the pituitary
2. Growth of the uterine endometrium and myometrium
Does the trophoblast only secrete hCG after implantation?
NO - it also makes Progesterone ane Estrogen!
How does the trophoblast make Progesterone?
By taking up LDL and converting LDL to cholesterol and progesterone.
WWhat does the placenta make more of; Prog or Estrogens?
Estrogens - enormous amounts!
What do you have to have to make Estrogens?
Can the placenta make Androgens?
No; it doesn't have all the steroidogenic enzymes to go through the whole pathway.
So where does the placenta get androgen substrate?
From the MATERNAL adrenal gland
How can the placenta convert Androgens from the mom to Estrogens in the baby?
Because it has lots of AROMATASE
What other tissue expresses aromatase?
Fat cells
Is testosterone the only androgen the placenta gets from the mom?
No it also gets DHEA
What does the fetal placenta convert Testosterone into? DHEA?
Testosterone -> Estradiol
DHEAs -> Estrone
What estrogen characterizes pregnant women?
What is estriol produced from?
How can the fetus make androgen?
From the fetal adrenal - the fetal zone produces huge amounts of DHEA and DHEAS
What is DHEAS?
A much more stable form of DHEA (sulfated)
What is DHEA?
a relatively weak androgen - doesn't really virilize unless it's 100000X higher like in CAH
What happens to DHEA and DHEAS produced in the fetal adrenal gland?
It goes to the fetal liver and gets hydroxylated to 16-OH DHEAs
What happens to 16-OH DHEAS?
That is the substrate for the placenta to make Estriol by its enzyme aromatase!
So which estrogens come from maternal androgens? Which comes from fetal androgen?
Maternal = Estradiol/Estrione
Fetal = Estriol
So what would indicate fetal brain damage?
Estriol lack in a pregnant woman - because the brain is not controlling androgen production.
When does hCG peak during pregnancy?
In the middle of the first trimester
Why don't we need hCG and the corpus luteum throughout the whole pregnancy?
Because the placenta gets big enough that it drives the production of progesterone and estrogen on its on; surpasses the amt produced by the CL.
Does hCG go all the way down to zero during the pregnancy?
No it's always measurable, but its much lower in the last 2 trimesters.
How do estrogen and progesterone levels change during pregnancy?
They increase progressively as the placenta secretes just a ton of them.
What happens to the anterior pituitary during pregnancy?
LH/FSH = Low/basal levels
Prl = rises progressivly to term
Why are LH/FSH low during pregnancy?
Because of suppression by the progesterone/estrogen produced by the CL (initially) and placenta.
So what is the most common cause of amenorrhea?
What does Prolactin do?
Stimulates the mammary glands to develop and become ready for partruition.
What gonadotropin comes from the placenta during pregnancy? When does it peak and then do?
hCG - peaks at 10 weeks and then reaches a new plateau.
What is hCS?
Human chorionic somatomammotropin!
What does hCS have homology with?
Growth hormone and prolactin!
Why is hCS an important placental secretion that increases with placental weight?
Because it works to maintain the mom's blood sugar and inhibit intermediate metabolism.
How does hCS maintain blood sugar in pregnant women?
By acting like growth hormone and promoting gluconeogenesis, which is counter-regulatory to insulin.
What is the result of increased gluconeogenesis due to hCS in pregnant women?
Most pregnant women are insulin resistant to some degree.
How do the concentrations of estrogens change in maternal blood during pregnancy?
They all increase to term
Which estrogen is produced from the fetal adrenals?
How does testosterone change in the maternal blood during pregnancy?
It increases to 10 TIMES PREPREGNANCY VALUES! Yikes probly get a moustache
Why does testosterone rise so much in pregnancy?
Because the placenta NEED that testosterone to produce estrogen
Where is the testosterone coming from in pregnant women?
The adrenals
What other endocrine organ function is EXTREMELY important in pregnancy?
Why is hyperthyroid functioning really bad?
How do you NOT detect hyperthyroid functioning in a pregnant women?
Why don't you measure T4 to test for hyperthyroidism in pregnancy?
Because you KNOW TBG is elevated, so you KNOW total T4 is elevated.
How DO you test for hyperthyroidism in pregnancy?
By measuring FREE T4
Why is total T4 elevated in pregnancy?
Because the enormous levels of estrogen produced by the placenta stimulate the liver to produce TBG.
Is T4 the only thing that goes up?
No, Total T4 AND T3 go up
What are normal preg. levels?
-Total T4
-Free T4
TBG = elevated
TT4 = elevated
FT4 = normal
TSH = normal
What are abnormal preg. levels?
-Total T4
-Free T4
TBG = elevated
TT4 = elevated
TSH = low