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LC 02 > Hu PLacental Devel and phys > Flashcards

Hu PLacental Devel and phys Flashcards

1
Q

ENdocrine fxn of placenta

A

Steroid and peptide hormone prod

- hCG + hPL

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2
Q

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

A

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

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3
Q

Placenta sim in between species?

A

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

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4
Q

What comprises the majority of hte placental mass?

A

Floating villi

- site of nutrient and waste exchange

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5
Q

Anchoring villi

A

attachment of placenta to uterus

  • site for invasive cytotrophoblast deployment
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6
Q

Interstitial invasion

A

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

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7
Q

Endovascular invasion

A

Cytotrophoblasts invade the uterine spiral arterioles through their superficial myometrial segments

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8
Q

Placenta fxn

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

*organ has finite life span

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9
Q

Diffusion limited transport is most affected by what?

A

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

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10
Q

Why is the fetal O2 diss curve shifted to left?

A

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)

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11
Q

Hepatic fxn of placenta

A

Metabolism

  1. Produces glycogen, cholesterol, FA
  2. Drug met (Enz for oxidation, glucuronidation, sulfation)
  3. Excretion of waste prod
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12
Q

Skin fxns of placenta

A
  1. Temp regulation
    - heat is prod by fetal metabolic processes
    - women feel warmer during preg
  2. Protective barrier to pathogens
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13
Q

Endocrine fxn of PLacenta

A
  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
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14
Q

In trisomy 21, what are hCG levels?

A

Elevated

  • hCG made by trophoblast cells
  • earliest it can be detected is 6-9 days post conception
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15
Q

human Placental lactogen (hPL)

A
  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
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16
Q

How does progesterone maintain pregnancy?

A

suppresses uterine contraction

17
Q

Does IgG or IgM cross placenta?

A

IgG

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

18
Q

Rh baby 2nd birth

A

With first birth, mom makes IgM
- no prob

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

19
Q

Amniotic fluid is made of?

A
  1. maternal plasma
  2. Fetal urine
  3. Fetal lung secretion
20
Q

causes of oligohydramnios

A
  1. Rupture of membranes
  2. Congenital anomalies (GU system)
  3. Nephrotoxic drugs (ACEi, NSAIDS)
  4. Poor placental perfusion
21
Q

Causes of polyhydramnios

A
  1. Congenital anomalies
    - make pee, cant swallow it
  2. Gestational diabetes
    - hyperglycemia has osmotic FX and draws in water –> distends uterus
22
Q

Prelacunar stage

  • what day?
  • What happens?
A

Days 6-8

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

23
Q

Which layer invades the adjacent maternal tissue

A

cytotrophoblasts proliferate

24
Q

Lacunae/trabecular stage

  • What day?
  • What happens?
A

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.

25
Q

Villous stage

  • What day
  • What happens?
A

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

26
Q

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

A

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.

27
Q

Umbilical arteries

- carries blood from where to where?

A

deoxygenated blood from fetus to placenta
*dives thru/pierces chorionic plate
(2)

28
Q

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

A

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

29
Q

Terminal villi

A

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

30
Q

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

A

1st 12 weeks;
An ultrafiltrate of maternal plasma

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

31
Q

Maternal causes of oligohydramnios

A
  1. Poor placental perfusion (pre-gestational diabetes)
  2. HTN
  3. Preeclampsia
32
Q

Placental causes of amniotic fluid disorders in oligohydramnios

A

Twin twin transfusion

33
Q

drugs that can cause oligohydramnios

A

Prostaglandin synthase inhibitors

ACE-inhibitors

*interferes with nl fetal renal fxn

34
Q

Rate limiting step of placental transport (for substances that cross the placenta slowly)

A

Rate of movement across the syncytiotrophoblast membranes between intervillous space and the fetal capillaries

*diffusion limited: direct dmg to syncytiotrophoblasts will affect oxygen transport to the fetus

35
Q

Rate limiting step of placental transport (for substances that cross the placenta rapidly)

A

Transport is dep on plasma concentration and rate of blood flow

*Flow limited: Pregnant women with aortic stenosis have reduced cardiac output –> growth restricted fetus

36
Q

Presence of IgM in fetus?

A

Response to congenital infxn

  • IgM cannot cross placenta
  • produced by fetus itself

*in its absence, IgG is the dom. Ig

LC 02 (15 decks)

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