Flashcards in Lecture 13 - Placenta III Deck (21):
Human chorionic Gonadotrophin (hCG)?
two chain hormone, shares alpha chain with TSH, LH and FSH, all hormones have unique beta chain, produced by pre-implantation zygot and placenta, detectable in mothers blood days after implantation
hCG concentration progression?
major rise following LMP, peaks around ned of 1st trimester where it flattens and then declines slightly
stimulate the production of progesterone and oestrogen by ovary during first 6-8wk pregnancy, doubles size of corpus luteum - essentially preventing uterus's normal cycle and causing CL to continually secrete p and oe to maintain endometrium into duodenal form
hCG and LH?
share same receptor, similar signalling pathway
Proof of importance of hCG in pregnancy?
vaccine of beta-hCG antibodies induces infertility
hCG and male fetuses?
LH-like activity stimulating testosterone synthesis by Leydig cells of fetal testis
Progesterone from placenta?
produces by syncytiotrophoblasts using LDL-cholesterol (no ovary dependence)
Functions of progesterone?
bind to receptors on glands and stromal cells in endometrium/decidua, maintain uterine inactivity (w oestrogen) for pregnancy environment
Oestrogen from placents?
cannot produce from scratch, modifies testosterone and other androgens, fetus produce these androgens but cannot convert, anencephalic pregnancies have low oestrogen
Primary maternal adaptations?
CVS, haemotological, immunity, genitals
dangerously elevated maternal blood pressure and protein in urine, exaggerated inflammatory response preventing normal vascular adaptation to pregnancy
increased stroke volume and pulse rate, decreased peripheral resistance (abnormally high in preeclampsia) - changes most important for first 9 weeks gestation
Oestrogen and CV changes?
reduce vascular resistance (mainly reproductive), alter type I:type II ratio of collagen in vessel wall - spiked levels not reached until 9wk where fetal adrenals form
levels increase in pregnancy, but effects appear blunted (likely due to receptor changes)
increase in blood volume, plasma faster than cells therefore reducing haematocrit
Blood loss during birth?
half litre (full in c section and twins), but hypervolaemia means loss leads to restoration of haemotocrit
Infections of increase severity in pregnancy?
increase in luteal phase and remainduring pregnancy, peak @ 30 weeks then rise again @ labour
th2 increase that support antibody imunity rather than th1 driven cell immunity
Presence of T cells in decidua?
not high, higher in repeated miscarraige, potentially attacks placenta