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Flashcards in Hu PLacental Devel and phys Deck (36)
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ENdocrine fxn of placenta

Steroid and peptide hormone prod
- hCG + hPL


What part of the placenta are in direct contact with maternal blood?

Fetal Trophoblast cells of the placenta are in dir contact w/ maternal blood
* Not fetal blood


Placenta sim in between species?

Not highly conserved
- wide variety
(shape, size, vascular, maternal-fetal connection, placental blood flow exchange system)


What comprises the majority of hte placental mass?

Floating villi
- site of nutrient and waste exchange


Anchoring villi

attachment of placenta to uterus

- site for invasive cytotrophoblast deployment


Interstitial invasion

cytotrophoblasts invade the entire endometrium and the first third of the myometrium


Endovascular invasion

Cytotrophoblasts invade the uterine spiral arterioles through their superficial myometrial segments


Placenta fxn

1. Transport
2. Respiration
(- drug met, glycogen form)
3. Hepatic
4. Skin
5. Endocrine
6. Immune syst

*organ has finite life span


Diffusion limited transport is most affected by what?

Syncytiotrophoblast membrane
- (vacuoles appear w/in syncytiotrophoblasts and eventually fuse to form lacunae --> lacunae make first contact with eroded endometrial capillaries)


Why is the fetal O2 diss curve shifted to left?

Fetus has Low affinity for 2,3 DPG
- fetus has higher O2 affinity! and is adequately oxygenated at low partial pressure
(at any oxygen tension and any pH)


Hepatic fxn of placenta

1. Produces glycogen, cholesterol, FA
2. Drug met (Enz for oxidation, glucuronidation, sulfation)
3. Excretion of waste prod


Skin fxns of placenta

1. Temp regulation
- heat is prod by fetal metabolic processes
- women feel warmer during preg

2. Protective barrier to pathogens


Endocrine fxn of PLacenta

1. Makes lots of hormones
2. Makes hCG
- peaks ~ 10 weeks
- maintains corpus luteum and progesterone prod until ~8 weeks when placenta can make enough prog.
- regulates cytotrophoblast differentiation into syncytiotrophoblast


In trisomy 21, what are hCG levels?


*hCG made by trophoblast cells
- earliest it can be detected is 6-9 days post conception


human Placental lactogen (hPL)

1. Prod by sCTB
2. Directs maternal system to shift more to FA met, making carbohydrates more available to fetus
3. Counter regulatory (anti-insulin) hormone
- Creates insulin resistance
- Partly responsible for development of gestational diabetes


How does progesterone maintain pregnancy?

suppresses uterine contraction


Does IgG or IgM cross placenta?


(makes sense, IgM is fucking huge)
- fetal immune system makes IgM


Rh baby 2nd birth

With first birth, mom makes IgM
- no prob

By second birth, mom makes IgG, cross placenta --> binds Rh factor --> fetal hydrops in Rh+ fetus


Amniotic fluid is made of?

1. maternal plasma
2. Fetal urine
3. Fetal lung secretion


causes of oligohydramnios

1. Rupture of membranes
2. Congenital anomalies (GU system)
3. Nephrotoxic drugs (ACEi, NSAIDS)
4. Poor placental perfusion


Causes of polyhydramnios

1. Congenital anomalies
- make pee, cant swallow it
2. Gestational diabetes
- hyperglycemia has osmotic FX and draws in water --> distends uterus


Prelacunar stage
- what day?
- What happens?

Days 6-8

Blastocyst attaches to endometrium and trophectoderm proliferates
- outer layer: syncytiotrophoblasts
- inner layer:


Which layer invades the adjacent maternal tissue

cytotrophoblasts proliferate


Lacunae/trabecular stage
- What day?
- What happens?

Day 9-12

Vacoules appear w/in the syncytiotrophoblasts and eventually fuse to form lacunae.
Syncytiotrophoblasts form pillars called trabeculae.
Lacunae make first contact w/ endometrial capillaries
This region will develop into intervillous space.

Implantation is complete at this point.


Villous stage
- What day
- What happens?

Day 13-18
Three stages:
First. Primary villous:
Cytotrophoblasts proliferate and begin to invade up the trabeculae.
Cytotrophoblast core is surrounded by syncytiotrophoblasts
Second. Secondary villi
- Extraembryonic mesoderm grows into cytotrophoblast and forms villous core
Third. Tertiary villi:
mesenchymal cells differentiate into blood vessels


How does the Materna-fetal circulation form from the floating/anchoring villi?

Cytotrophoblasts form at the tip of the FV and AV, and makes contact with the decidua.

Cytotrophoblasts invade thru the decidua to the inner 1/3 of the myometrium and remodel the uterine spiral arteries.


Umbilical arteries
- carries blood from where to where?

deoxygenated blood from fetus to placenta
*dives thru/pierces chorionic plate


What happens once the umbilical arteries and veins pierce through the chorionic plate?

They branch and form capillary networks w/in the chorionic villi.
- maternal bvs are in the intervillous space and provides O2 to fetal blood in the villi

*There is no direct mixing of maternal and fetal blood


Terminal villi

Have lots of capillaries and highly dilated sinusoids

The Location where most of the villous growth and transplacental transport takes place

Minimizes transit distance between fetal and maternal circulations


What is the amniotic fluid made up of early in pregnancy vs later?

1st 12 weeks;
An ultrafiltrate of maternal plasma

>12 weeks:
fetal kidneys start working
- fetal urine
- sm amts of fetal lung secretions