placentation Flashcards
what happens by day 12
embryo is completely embedded in decidua
what does the chorion do
releases enzymes and expands
erodes decidua capillary wall - maternal blood leaks surrounding the embryo
finger like projection of chronic tissue extend into the pools to form placneta villi
what happens week 4
foetal blood supply has deveolped
what happens week 5
placenta is functioning
what happens after week 8
embryo -> fetus
what are the functions of the placenta
digestive, respiratory and kidney systems for the fetus
temporary endocrine organ (hormones)
what hormones are released from the placenta
HCG
oestrogen
progesteron
what does HCG do
prolongs the life of the corpus luteum
what does oestrogen do
growth of myometrium
development of mammary glands
contractile activity of uterus
increases myometrial responsiveness to oxytocin
increases prolactin secretion from AP
suppresses lactation
what deos progesterone do
prevents miscarriage - supressess uterine cotactions
mucous plug in cervical canal
development of milk glands
supresses lactation
why cants the foetus supply oestrogen
lacks enzymes required
exposure to dangerously high levels of hormones not required by foetus
what is the maternal - placenta foetal unit problem
mother requires oestrogen adn progesterone from placenta
placenta cannot synthesis enough cholesterol to produce steroid oestrogen
foetus cannot syntheisse progesterone
what is the MFP solution
mother supplies most cholesterol to placenta
foetal adrenal glands and liver have missing enzymes - produces precursors for oestrogen synthesis
placenta generates progesterone - exports to mother and placenta
