Physiology of Fetus and Placenta Flashcards

1
Q

Three fetal ducts that maximize blood flow to fetus brain and coronary arteries and circulation

A

Placenta –> umbilical vein (most oxygenated) –> shunted past liver via ductus venosus –> IVC –> right atrium (some mixing of blood) –> 1, new blood from IVC: foramen ovale –> left atrium –> left ventricle –> aorta –> brain and 2, deox blood from brain: right ventricle –> pulmonary artery –> ductus arteriosius –>descending aorta –> umbilical arteries –> placenta

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2
Q

Which fetal vessel has the most oxygenated blood for fetus

A

umbilical vein

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3
Q

Which fetal vessels take blood to the placenta

A

umbilical arteries

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4
Q

Where in the fetal heart is blood mixed?

A

right atrium –> return blood from brain and higher oxygen “fresh” blood from IVC –> some mixing but currents ensure most brain blood gets to right ventricle and most fresh blood gets to left atrium

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5
Q

When baby is born and cord is clamped ____ regresses

A

ductus venosus

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6
Q

When baby is born and takes first breath ____ dilate and ____ constricts.

A

vessels going to lung dilate and ductus arteriosus constricts

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7
Q

How does fetus avoid rejection by mother

A

HLA-G is not recognized by nonself MHC I and protects against NK cell attack

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8
Q

_____ is the primary site of placental hormone production

A

syncytiotrophoblast

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9
Q

HCG

A

single alpha subunit common to LH/FSH/TSH –> chr6; cluster of 7 beta units, chr19

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10
Q

T/F women in early pregnancy can be hyperthyroid

A

T –> because of shared alpha subunit with HCG

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11
Q

When can hCG be detected in maternal serum?

A

8 days after ovulation

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12
Q

After implantation, _______ produce most of the fetal hCG

A

villous syncytiotrophoblast

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13
Q

maternal serum levels of hcg _____ every 1.4 days during pregnancy

A

double –> peak at 10 weeks and the ndecline

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14
Q

Roles of hCG

A

maintain corpus luteum –> LH/CG receptor activates adenylyl cyclase and steroidogeneis; binds to TSH receptors

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15
Q

T/F antisera to hCG in early gestation causes pregnancy termination

A

T

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16
Q

____ test helps distinguish between intrauterine and ectopic pregnancy

A

hCG doubling time + ultrasound

17
Q

MMS: multiple marker screening

A

bunch of fetal proteins that can be screened that indicate potential genetic issues

18
Q

T/F fetal and placental compartments must work together to make estrogen because each are missing one enzyme.

A

T

19
Q

Fetal adrenal makes ___ which goes to the placenta to be made into _____

A

dhea and estradiol

20
Q

T/F fetus never makes cortisol

A

T –> no negative feedback to fetal pituitary so always pumping out DHEA

21
Q

Placenta is the major source of _____

A

progesterone

22
Q

2 roles of progesterone

A

during luteal phase, prepares endometrium for implanation, and prevents maternal immune rejection of trophoblast (because inhibits hte production of cytolytic cytokines)

23
Q

T/F progesterone is a smooth muscle relaxant

A

prevents gap junction formation in muscle, reduces calcium channel synthesis, and decreases oxytocin receptors –> reduces muscle tone –> side effects = heartburn, urine stasis/utis, etc

24
Q

____ estrogen is almost exclusively derived from fetal adrenal while ____ estrogen is equivalently derived from maternal and fetal systems

A

estriol vs estradiol

25
Q

2 zones of fetal adrenal cortex

A

thick inner fetal and thin outer definitive zones

26
Q

Thick inner fetal zones

A

> 80% of the bulk of the gland, rapidly involutes after delivery, produces lots of DHEA, minimal production of cortisol

27
Q

______ stimulates fetal adrenal to conduct steroidgenesis

A

ACTH –> not inhibited because of low fetal cortisol + placental deactivation of maternal cortisol

28
Q

Actions of estrogens

A

fetal control of maternal physiology, vasodilation of spiral arteries, parturition (placental CRH, myometrial gap junctions, mammary epithelial proliferation)