Physiology of Fetus and Placenta Flashcards
Three fetal ducts that maximize blood flow to fetus brain and coronary arteries and circulation
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
Which fetal vessel has the most oxygenated blood for fetus
umbilical vein
Which fetal vessels take blood to the placenta
umbilical arteries
Where in the fetal heart is blood mixed?
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
When baby is born and cord is clamped ____ regresses
ductus venosus
When baby is born and takes first breath ____ dilate and ____ constricts.
vessels going to lung dilate and ductus arteriosus constricts
How does fetus avoid rejection by mother
HLA-G is not recognized by nonself MHC I and protects against NK cell attack
_____ is the primary site of placental hormone production
syncytiotrophoblast
HCG
single alpha subunit common to LH/FSH/TSH –> chr6; cluster of 7 beta units, chr19
T/F women in early pregnancy can be hyperthyroid
T –> because of shared alpha subunit with HCG
When can hCG be detected in maternal serum?
8 days after ovulation
After implantation, _______ produce most of the fetal hCG
villous syncytiotrophoblast
maternal serum levels of hcg _____ every 1.4 days during pregnancy
double –> peak at 10 weeks and the ndecline
Roles of hCG
maintain corpus luteum –> LH/CG receptor activates adenylyl cyclase and steroidogeneis; binds to TSH receptors
T/F antisera to hCG in early gestation causes pregnancy termination
T
____ test helps distinguish between intrauterine and ectopic pregnancy
hCG doubling time + ultrasound
MMS: multiple marker screening
bunch of fetal proteins that can be screened that indicate potential genetic issues
T/F fetal and placental compartments must work together to make estrogen because each are missing one enzyme.
T
Fetal adrenal makes ___ which goes to the placenta to be made into _____
dhea and estradiol
T/F fetus never makes cortisol
T –> no negative feedback to fetal pituitary so always pumping out DHEA
Placenta is the major source of _____
progesterone
2 roles of progesterone
during luteal phase, prepares endometrium for implanation, and prevents maternal immune rejection of trophoblast (because inhibits hte production of cytolytic cytokines)
T/F progesterone is a smooth muscle relaxant
prevents gap junction formation in muscle, reduces calcium channel synthesis, and decreases oxytocin receptors –> reduces muscle tone –> side effects = heartburn, urine stasis/utis, etc
____ estrogen is almost exclusively derived from fetal adrenal while ____ estrogen is equivalently derived from maternal and fetal systems
estriol vs estradiol
2 zones of fetal adrenal cortex
thick inner fetal and thin outer definitive zones
Thick inner fetal zones
> 80% of the bulk of the gland, rapidly involutes after delivery, produces lots of DHEA, minimal production of cortisol
______ stimulates fetal adrenal to conduct steroidgenesis
ACTH –> not inhibited because of low fetal cortisol + placental deactivation of maternal cortisol
Actions of estrogens
fetal control of maternal physiology, vasodilation of spiral arteries, parturition (placental CRH, myometrial gap junctions, mammary epithelial proliferation)
