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18 Cards in this Set
- Front
- Back
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What produces hCG and what receptor does it use?
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SyncytioTB cells; LH/hCG joint R
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What are 2 fxns of hCG?
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Promotes progesterone production by the corpus luteal cells from 3-7 weeks of gestation; Cytotrophoblast cell hCG promotes implantation of the blastocyst
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What is the mechanism of hCG production? What is this similar to?
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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
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What is the difference between LH & CG in humans/ primates and all other species? What is the role of progesterone in all species?
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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.
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Why are LH & CG so similar?
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CG was created due to a point mutation of LH at evolution of the first primate.
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What is the difference between hCG & LH?
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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.
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In the first trimester, hCG levels double q2d, then decline dramatically to 1/5 peak level b4 the 2nd trimester. Why?
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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.
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How does hCG produced by intermediate syncytioTB affect hCG levels?
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Feeds back on less fused cells to increase hCG. It also promotes further fusion, leading to post-peak decline.
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What is the difference between hCG made by syncytioTB cells and cytoTB cells? What does this cause?
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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.
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What is the therapeutic use of hCG?
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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.
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What is the only accurate way of demonstrating or excluding pregnancy? Why?
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Lab serum quantitative test (detects >95% on 1st d of missed menses). POC (55-80%) & OTC (>95-<16%) tests are rough indicators only.
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How is progesterone made by the trophoblast?
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From maternal cholesterol. Chol (mom) -> Chol (placenta) -> (CSCC) Preg(p) -> Prog(p) -> Prog(mom)
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How does the placenta/ trophoblast make estrogens?
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It doesn't. Placenta can't make androgens, so estrogen is made by the fetus.
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How are E1 (estrone) & E2 (estradiol) made by the placenta?
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DHEA-S from mom's & fetal adrenals go to placenta to make estrone & estradiol, which goes back into mom's circ.
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What is the primary type of estrogen made by the placenta & how can this be used clinically?
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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.
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How is E3 made during pregnancy?
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Chol (mom) -> Preg (plac) -> 16-a-DHEAS (fetus) -> Estriol (fetus) -> Estriol (mom)
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What is hPL? What is it produced by? What is it similar to?
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Human placental lactogen; Produced by syncytioTB cells; acts like hCG
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What are the functions (2) of hPL?
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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.
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