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39 Cards in this Set

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