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18 Cards in this Set

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What produces hCG and what receptor does it use?
SyncytioTB cells; LH/hCG joint R
What are 2 fxns of hCG?
Promotes progesterone production by the corpus luteal cells from 3-7 weeks of gestation; Cytotrophoblast cell hCG promotes implantation of the blastocyst
What is the mechanism of hCG production? What is this similar to?
Similar to LH prodxn of Prog/ Androstenedione. Chol(e) -> Chol (i) -> Chol (mito) -> (PCyt 450 & CSCC) Preg(mito) -> Progesterone (cyto) -> Prog (e). Via LH/hCG GPCR which increases AC, cAMP, & PK phosphorylation of mito
What is the difference between LH & CG in humans/ primates and all other species? What is the role of progesterone in all species?
LH is secreted by the placenta in all animals except humans & primates. CG is secreted by the placenta only in primates & humans & takes over from LH promotion of progesterone production by corpus luteum. P promotes vascularization of placenta during pregnancy & blocks immune rejxn of placenta.
Why are LH & CG so similar?
CG was created due to a point mutation of LH at evolution of the first primate.
What is the difference between hCG & LH?
LH has a pl of 8.0 & a circulating t1/2 of 20m. CG has a pl of 3.5 & a circulating t1/2 of 37h. CG is >100x more biologically active than LH.
In the first trimester, hCG levels double q2d, then decline dramatically to 1/5 peak level b4 the 2nd trimester. Why?
hCG levels increase as syncytioTB fuses. hCG max's at intermediate syncytioTB level. Once it is fully fused & compressed (fully differentiated), hCG levels reduce again.
How does hCG produced by intermediate syncytioTB affect hCG levels?
Feeds back on less fused cells to increase hCG. It also promotes further fusion, leading to post-peak decline.
What is the difference between hCG made by syncytioTB cells and cytoTB cells? What does this cause?
hCG variant made by cytoTB cells is hyperglycosylated. This hCG is the signal for the malignancy-like invasion at implantation. Also causes a 2nd implantation that occurs only in humans(not other primates) ~13-16w gestation, which is an angiogenic implantation that gives the vascular supply needed for development of an advanced species.
What is the therapeutic use of hCG?
Promotion of ovulation for infertility, artificial insemination, or anovulation, or promotion of polyovulation to collect ova for IVF. Better than LH bcs of >t1/2.
What is the only accurate way of demonstrating or excluding pregnancy? Why?
Lab serum quantitative test (detects >95% on 1st d of missed menses). POC (55-80%) & OTC (>95-<16%) tests are rough indicators only.
How is progesterone made by the trophoblast?
From maternal cholesterol. Chol (mom) -> Chol (placenta) -> (CSCC) Preg(p) -> Prog(p) -> Prog(mom)
How does the placenta/ trophoblast make estrogens?
It doesn't. Placenta can't make androgens, so estrogen is made by the fetus.
How are E1 (estrone) & E2 (estradiol) made by the placenta?
DHEA-S from mom's & fetal adrenals go to placenta to make estrone & estradiol, which goes back into mom's circ.
What is the primary type of estrogen made by the placenta & how can this be used clinically?
E3 (10% potency) is the principal estrogen made during pregnancy. It is only made from fetal 16-alpha hydroxyDHEA-S, so it is a useful test for fetal progress & fetal placental unit intactness.
How is E3 made during pregnancy?
Chol (mom) -> Preg (plac) -> 16-a-DHEAS (fetus) -> Estriol (fetus) -> Estriol (mom)
What is hPL? What is it produced by? What is it similar to?
Human placental lactogen; Produced by syncytioTB cells; acts like hCG
What are the functions (2) of hPL?
Acts like hCG in pregnancy, raising maternal glc levels to provide essential glc to the fetus for anabolism & growth. Raised maternal glc also provides glc for lactose formation in milk.