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39 Cards in this Set
- Front
- Back
placenta
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apposition of fetal and parental tissues for purposes of physiological exchange and hormonal production
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what does the placenta do?
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nutrient and gas exchange between mother and fetus
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when is placenta formed
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when syncytiotrophoblast is invading endometrium
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what does trophoblast become in the placenta?
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villous chorion
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main components that form placenta?
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syncytiotrophoblast and cytotrophoblast
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where does placenta form within uterus?
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where decidua basalis is (i.e. where embryo has implanted this is where material exchange takes place between mother & fetus)
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layers of placental barrier
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maternal blood, syncytiotrophoblast, cytotropoblast, extracellular space, endothelium of fetal blood vessels, fetal blood
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before the formation of the placenta, how does the fetus survive
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from uterine secretions from the uterine glands up until day 13
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endometrium called what in pregnancy
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endometrium decidua
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what is the baby encased within
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tough layer of membrane amnion
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chorion def.
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extra-embryonic mesoderm and two layers of trophoblast forms the chorionic sac
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what is contained within the chorion
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the embryo with amniotic and yolk sacs are susbended by a connecting sac within the chorionic cavity
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inspection of placenta look for?
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IS IT whole, divided into cotyledons, (which could break off in uterus)VESSELS: umbilicus in middle, 2A, 1V
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placenta measurement at 10wks
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6.5mm
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placenta measurement at 15 weeks
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15cm
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special about placenta?
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HIGHLY VASCULAR huge surf. area exh. site for nutrients
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If one umbilical artery instead of two?
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could be something wrong with baby
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If too many red cells in baby problem?
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potential for clotting
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only single artery in placenta - % and type of problems
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16%premature, 17%abnormal, 34% small baby
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early form of monozygotic twin
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2 different blastocysts from same egg (cytokinesis)
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most common form of monozygotic twin
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one blastocyst, two amniotic cavities, shared placenta
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later form of monozygotic twin can give rise to
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siamese twins 2 bilaminar discs within 1 blastocyst
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Of 100 good eggs, % that wont fertilize
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15%
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of 100 good eggs, % that wont implant
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15%
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of 100 good eggs, % that cause cessation of menses
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42% (i.e. pregnancy survives)
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of 100 good eggs, % that will die in wks 3 6
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8%
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of 100 good eggs, % that will be born late or stillborn
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3
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of 100 good eggs, how many born alive
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31
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of the 31 live-born from 100 good eggs, how many will die or be abnormal
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3 abnormal, 1 may die
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surviving pregnancies, statistically, from 100 good eggs.
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28 normal.
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what might cause cessation of pregnancies?
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chromosome abnormality or mutation 25%, radiation 1%, infections 2 3%, drugs and chemicals 4 5%, combinations & unknowns 60 70%
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60 70% of early abortions due to
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chromosomal disorders: trisomy 50%, polyploidy 25%, 45 + X 25%
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terathanasia
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monster death: tera= monster, thanatos=death
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Of spina bifida cases, what % dies?
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90%
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Teratology principles effects of teratogens vary how
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with genetic makeup, time of exposure most critical weeks are early on, esp. 1st trimester, dosage
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complications with teratogens
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may not effect mother at all, single teratogen may produce many different malformations, several teratogens may produce same defect, but by different mechanisms
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common potent teratogens
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Retinoids and skin care
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Retinoids cause defects of
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CNS, face, ears, heart, kindey, esophagus, thymus. Cause spontaneous abortions.
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Animal testing of teratogens
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doesnt accurately reflect human results isnt useful due to genetic differences
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