Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
19 Cards in this Set
- Front
- Back
|
describe formation of zygote, morula, embryo, and trophoblast
|
HY Embryo: p. 12
1.egg becomes fertilized in fallop tube==>zygote 2. enters uterine cavity as solid mass of cells (morula) 3. fluid accumulates within cell mass: -inner cell mass: embryo -outer cell mass: trophoblast 4. b/w inner cell mass (embryo) and trophoblast, the amniotic cavity forms 5. outer cell mass (trophoblast) invades the endometrium |
|
|
types of trophoblasts in placenta parenchyma:
|
CYTOTROPHOBLAST gives rise to:
-intermediate trophoblast (invades uterus & vessels) -syncytiotrophoblast (lines placental villi and provides transfer from maternal to fetal compartment) |
|
|
what blood does the syncytiotrophoblast have contact with?
|
The syncytiotrophoblast is bathed by maternal blood. it is separated from fetal blood by endothelial cells.
|
|
|
fetal membranes
|
*genetically identical to fetus
*avascular, no nerve cells 2 layers: 1. amnion (inner)- surrounds amniotic cavity 2. chorion (outer)-attaches to decidua (bv, etc.) *The amnion and chorion fuse at 13-14 wks |
|
|
-when do fetal membranes (chorion/amnion) rupture?
-What causes this? |
-fetal membranes (chorion/amnion) rupture near delivery.
-Caused by: *MMP's (Matrix Metalloproteinases--break down proteins in ECM) Inflammatory: *TNF-alpha (increase collagenase activity & activate inflammatory pathways) *IL1 (ditto) *PGE2, PGF2 (ditto) |
|
|
placental fxn
|
-maintains preg and fetus
-1st trimester: produce hormones -2nd-3rd trimesters: nutrient transfer b/w mother and fetus: 1.Transit across placental membranes a.passive diff, facil diff b.active transport (glucose, certain aa, Ca2+) c.endocytosis, exocytosis (IgG, LDL) 2. Eliminate waste products -fetal liver immature -eliminates bile acids 3.Respiratory fxn -rapid diff -HbF has higher aff for O2 and lower aff for CO2 |
|
|
risk factors for placenta previa
|
-previous placenta previa
-multiple gestation -smoking |
|
|
vasa previa
|
"vasa"=vessels
"previa"=cover cervical os -fetal vessels ("vasa"=vessels) traverse the membranes in lower uterine segment and cover the cervical os ("previa"=cover cervical os) |
|
|
placenta abruption
-def? -et? |
premature separation of the normally implanted placenta
-often caused by adherent retro placental clot |
|
|
risk of placenta abruption
|
-mult gestations
-HTN -maternal trauma -maternal smoking |
|
|
what is functional unit of placenta
|
chorionic villi
|
|
|
where are placenta and fetal membranes derived from?
|
fetal tissues
(fetal membranes=amnion & chorion) |
|
|
is there direct mixing of maternal and fetal blood
|
no.
|
|
|
complications of abnl placental implantation (previa, accreta) or early placental separation?
|
significant maternal hemorrhage
|
|
|
what can cause significant maternal hemorrhage?
|
complications of abnl placental implantation (previa, accreta) or early placental separation
|
|
|
monozygotic pregnancy, timing of cleavage of fertilized ovum
|
better to cleave the fertilized ovum SOONER:
-days 2-3: 2 chorion, 2 amnion -days 3-8: 1 chorion, 2 amnion -days 8-13: 1 chorion,1 amnion -days 13-15:conjoined twins |
|
|
what is the greatest perinatal mortality risk?
|
monoamniotic twins (1 amnion): perinatal mortality risk is >20%
|
|
|
what is risk for monochorionic, diamniotic twins?
|
-risk d/t "sharing" a placenta:
==>unequal distrib of blood b/w twins |
|
|
Placenta previa
|
=implantation of placenta over cervical os
1.Total placenta previa: placenta completely covers cervical os 2.Partial placenta previa: partial occlusion of cervical os 3. Marginal placenta previa: placenta encroaches on margin of cervical os *Placenta forms abnl attachment to uterine wall *Absence of decidua basalis (=maternal portion of placenta; =uterine lining (endometrium) during preg) *Types (from better to worse, more common to less common) 1."A"ttached directly to myometrium ("A"ccreta) 2."IN"vade myometrium ("IN"creta) 3."PE"netrate myometrium ("PE"rcreta) |
