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