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Reproduction Week 3 > Lecture 35: Physiology of Fetus and Placenta > Flashcards

Lecture 35: Physiology of Fetus and Placenta Flashcards

1
Q

Where does the fetus develop from?

A

The inner cell mass

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2
Q

What part of the placenta is closest to fetus?

A

Amnion

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3
Q

What part of placenta is closest to mother?

A

Decidua basalis

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4
Q

What part of placenta is in the middle?

A

Chorion

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5
Q

How many cells are the fetal blood and the maternal blood separated by?

A

2 cells in width

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6
Q

What are the three adaptations that allow fetal circulation to take place in placenta than lungs?

A
  1. ductus venosus (takes blood away from liver)
  2. foramen ovale
  3. ductus arteriosus (shutns blood from right ventricle and pulmonary artery to descending aorta
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7
Q

What are the two characteristics of placental blood exchange?

A

Increased blood flow from mom the fetus

Surface exchange rate (the idea is to get mothers blood closer to baby’s blood to increase this rate)

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8
Q

What is the umbilical vein of fetus?

A

PO2 = 30%

This is the most oxygenated part of the circulation of fetus

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9
Q

When is hCG detected? What happens if you have abnormal hCG doubling?

A

8 days

Abnormal doubling = ectopic pregnancy

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10
Q

What are the 3 adaptations the baby ahs to counter the low PO2?

A
  1. fetal hemoglobin
  2. fetal heart pumps fast
  3. ductus venosus, foramen ovale, ductus arteriosus
    • shunts that make sure the blood stays oxygenated
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11
Q

What are the functions of placenta?

A
  1. hormone production
  2. nutrient transport
  3. Prevents immune rejection
    • HLA-G
  4. waste excretion
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12
Q

What is the primary site of hormone production in placenta?

A

Syncytiotrophoblast
Hormones released into maternal circulation
Estrogen and progesterone

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13
Q

What is the purpose of the hCG?

A
  1. maintain the corpus luteum
    -LH/CG receptor
    -activation of adenylyl cyclase
    -steroidogenesis
  2. antisera to hCG in early gestation causes pregnancy termination
  3. binds to TSH receptors
    Creates a “favorable environment” which means we don’t know shit
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14
Q

What is CVS?

A

Chorion villus sampling

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15
Q

What is the HIV transmission rate of woman to baby?

A

25%

That’s astounding!

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16
Q

What is the physiologic role of progesterone in pregnancy?

A
  1. maintains endometrium and endometrial blood supply

2. inhibits myometrial contraction (along with relaxin)

17
Q

What is the importance of the fetal adrenal gland?

A

Fetal adrenal gland must work TOGETHER with placenta to make estrogen

18
Q

What does placenta lack? Can make what?

A

P450c17

Makes progesterone and gets stuck

19
Q

What does fetal adrenal gland make? What does it lack?

A

It makes DHEA

Lacks 3beta HSDII

20
Q

How does placent and fetal adrenal glands work together to make estradiol?

A

DHEA in fetal adrenal glands gets transported to placenta

Placenta has 3beta HSDII which allows the DHEA to be converted to estradiol!!

21
Q

What is the role of ACTH in fetal development?

A

It signals fetal adrenal gland to produce DHEA

22
Q

What happens when you have anencephaly in the fetus?

A

No ACTH so no DHEA being made

That means adrenal atrophy after 20 weeks

23
Q

What is the significance of fetal adrenal cortex LACKING 3bHSDII?

A

It means that pregnenolone cannot be converted to cortisol
This means that there is no negative feedback and you can continue to form DHEA which gets converted to estradiol in placenta

24
Q

What do you measure to gauge fetal placental estrogen production?

A

Estriol (E3)

90% of estriol in mother’s body is from fetus

25
Q

What does 11betaHSD in placenta do?

A

Deactivates maternal cortisol

That means if you give steroids to baby, you know it can break it down

26
Q

What is significant about fetal adrenal cortex?

A
  1. thick inner fetal zone
    • 80% of gland and involutes after delivery
    • abundant P450c17 activity so produces a lot of DHEAS
    • minimal 3BHSD activity so little cortisol
  2. thin outer definitive zone
27
Q

What is the significance of DHEA?

A

Precursor to androstenedion/estradiol

28
Q

What are the side effects of progesterone?

A

Easier to get UTI

29
Q

Where does maternal-fetal exchange take place?

A

Maternal-fetal exchange of nutrients and waste occurs within the placental villi

30
Q

Where is Placental hormone secretion directed?

A

Is directed toward the maternal blood stream

31
Q

How do steroids get produced in placenta?

A

Placental steroid production requires coordinated cholesterol metabolism in the fetal adrenal glands and placenta

32
Q

What does estrogen do?

A
  1. placental CRH
  2. myometrial gap junctions
  3. mammary epithelial cell proliferation
  4. vasodilation of spiral arteries

Reproduction Week 3 (8 decks)

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