• Created by: LUFCMazza
  • Created on: 13-08-20 13:53
only found in mammals and have a torphoblast which forms a relationship with maternal endometrium
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function of trophoblast in humans
phusical attachemnt of conceptus to uterus, inasion of endometriual tissue and other ***** tooo
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Fetal membranes...
Chorion, allantois, yolk sac and amnion
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trophoblast + extra embryonic mesodemr, forms chorionic veiscle inc placenta
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endoderm lining, mesodermal coveirng, forms blader and urachus
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yolk sac...
haemopoiesis in early pregnancy, development of gut, primordial grm cells
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main source of amniotic fluid in early pregnancy (later form urine, lung, skin). Amniotic fluid -- 1L at temr, turnover time 3h
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What are the stages of placental development?
Previllous embryo-- no villi, cytotrophoblast covered with syncitiotorphoblast
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1y villi
defined cytotrophoblasic projectiosn covered by syncitiotropho
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mesenchymal core
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mesenchyme invaded w fetabl blod vessles
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placental blood flow- placental intervillous spaces receive
blood form branches of umbilicar arteries (from intenral iliac) carrying deoxygenated blood.
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venous blood from placenta passes via umbilical vein to liver (through passed by ductus venosus) adn from there to right atrium
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blood enters intervillous spaces from the
spiral arteries
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what sourt of flow in intervillous space?
countercurrent flow
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blood leaves intervillous spaces via
uteirne arteries
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fetus grows relativley faster than placenta. how
branching of villia nd brush border, decerase in vollois diamate, thinnign of barrier
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What sort of substances concentrated in fetal circulation
Fe, Ca , Cu glucose Vi B12, folate, riboflavin, vit C, aa and hormones etc.
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what confers passive immunity to fetus
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what preserves corpus luteums release of progesterone?
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what prepares for initation of parturition?
oestradiol induces production of contraction-associated proteins by the myometrium
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what does hPL aka human chorionic somatomammotrophin do?
It is similar to GH and PRL- it increases maternal lipid breakdown to provide fetus with energy
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preoparing for and iitation of partuirtiaion
y; • preparing for & initiation of parturition. Oestradiol induces production of contraction-associated proteins by the myometrium, stimulates production of oxytocin receptors; and increases the excitability of the myometrium. Placental CRH (produced
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myometrical contraciton and cervix?
Placental prostaglandins (PGE2 and PGF2) act in this way; (earlier in pregnancy the relaxant prostagla. PGI2 is a relaxamt earleir on
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prep for lactaiton
oestradiol stimulates development of the duct system of the mammary gland; progesterone causes development of the alveoli; hPL has a lactogenic action, developing the secretory potential of the breast alveoli; however, during pregnancy, production of
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Production of estradiol
Although the placenta can produce progesterone from cholesterol, the primate placenta does not have the key enzymes necessary to produce estradiol from cholestero.l (17-hydroxylase; 17
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Instead it uses the weak androgen dehydroepiandrosterone (DHEA) which is synthesized in the fetal adrenal gland. This is converted by the placenta in part to estradiol. However, it is also 16- hydroxylated by the liver, to yield a steroid which is co
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function of trophoblast in humans


phusical attachemnt of conceptus to uterus, inasion of endometriual tissue and other ***** tooo

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Fetal membranes...


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