Fetus & Placenta Flashcards
gestational length of pregnancy
40 weeks from onset of LMP
fertilization length of pregnancy
38 weeks from fertilization (woman is already 2 weeks pregnant at first missed period)
what week does fetal period begin?
9 weeks
When do most malformations occur?
during embryonic period
first trimester key points
ossification centers have formed, eyelids fused, fetus active but not big enough to feel, external sexual differentiation, herniated intestinal loop returns to abdominal cavity
second trimester key points
fetus practices sucking and other reflexes, swallowing, urinating, breathing, hair on head and face, lanugo hair around body, surfactant in lungs, vernix caseosa around skin, meconium in large intestine
polyhydramnios
too much fluid, swallowing impaired
oligohydramnios
too little fluid, urination impaired
results of oligohydramnions
Potter’s syndrome; clubbed feet, pulmonary hypoplasia, cranial anomalies
vernix caseosa
sebaceous gland secretions mixed with sloughed epidermal cells; lubricate skin
meconium staining
green/yellow amniotic fluid at birth; indicator that baby was stressed in utero
third trimester key points
all second trimester features, most of fat and weight added, more surfactant in lungs
amniocentesis for lung maturity
can be used to measure amount of surfactant
chorion frondosum
part of chorion with villi
chorion laeve
part of chorion without villi
fetal exchange villus
losses cytotrophoblast and connective tissue to allow for more rapid exchange
embryonic exchange vills
syncytium, cytotrophoblast, endothelium, connective tissue
decidua
renamed endometrium
decidua capsularis
portion underlying chorion laeve
decidua basalis
where moms blood is going to be circulating into the placenta
decidua parietalis
everything else associating with uterine wall
chorion
completely embedded in the endometrium at this point
What membranes breaks when water breaks?
chorion laeve and amnion
cotyledons
groups of villi
umbilical cord
amnion on surface and vessels associated with it; intestinal loop, allantois, vessels
umbilical vein
supplies oxygen from placenta to fetus
umbilical arteries (2)
return deoxygenated blood from fetal internal iliac arteries to placenta
Where do umbilical arteries and veins derive from?
allantois
first stage of parturition (labor & delivery)
dilation of the cervix from uterus contraction, water breaking
second stage of parturition
delivery of fetus
third stage of parturition
delivery of placenta and membranes
dizygotic
fraternal
fraternal twins
a. dichorionic, diamnionic with own placenta
b. dichorionic, diamnionic with shared placenta
monozygotic
identical
identical twins
a. splitting at 2 cell stage; own placenta, diamnionic, dichorionic
b. splitting at early blastocyst; common placenta and chorion, separate amnions
c. splitting at later blastocyst; sharing everything, most dangerous
most identical twins are _
monochorionic, diamnionic
transfusion syndrome
one twin gets more blood than the other; much larger
drugs between 0-2 weeks
fatal
drugs between 3-8 weeks
will result in malformations, embryo is very sensitive to insult
drugs between 9-38 weeks
embryo less sensitive; usually just problems with organ growth or function
chorionic villus
can be done before amniocentesis is an option or if too little amnionic fluid
