Physiology of the Placenta Flashcards
Placenta comes from the Greek term for ___________.
flat cake
The lining of the cavity that the fetus is in (between the fetus and the uterus) is the ___________.
amnion
What is the division between the fetus and the placenta?
The chorionic plate
One of the difficulties of placental research is _______________.
that no animal has a perfectly analogous placental system (the placenta is not a perfectly conserved organ)
Implantation occurs _________.
during day 6-8
The arteriocapillary network begins to form during the _________ stage.
tertiary villi
The majority of placental mass is _____________.
floating villi, where nutrient and waste exchange occur
Which cells are in the deepest part of chorionic invasion?
Cytotrophoblasts
The ____________ invade and make contact with the maternal circulation.
syncytiotrophoblasts
Describe the three kinds of transport across the placenta and give an example of each.
- Passive diffusion: H2O, gases
- Facilitated diffusion: glucose
- Active transport: amino acids
Note: passive diffusion is perfusion-limited and active diffusion is membrane-limited
hCG levels correlate with _______________ during the late first trimester.
morning sickness
Which endocrine hormone suppresses uterine contractions?
Progesterone
3-beta hydroxysteroid dehydrogenase converts ______________.
pregnenolone to progesterone (and DHEA to estradiol)
Two vaccinations are recommended during pregnancy for the immune benefit of the fetus: ______________.
TDaP and influenza
What is the volume of the amniotic fluid over the pregnancy?
- 250 mL at 16 weeks
* 1 liter at birth
What three things can cause polyhydramnios?
- Gestational diabetes
- Neural tube defects (anencephaly)
- Esophageal atresia
Maternal blood comes in direct contact with _____________.
trophoblasts
From day 9 to day 12, the syncytiotrophoblasts form trabeculae. Between these are ______________.
vacuolized lacunae which holds blood (this is the intervillous space)
From day 13 to day 18, the primary villi form. What two cells make up the villi?
During this stage, called the villous stage, cytotrophoblasts invade the trabeculae which are made of syncytiotrophoblasts. These become the villi. (Thus, primary villi are made of syncytiotrophoblasts around cytotrophoblast cores.)
What’s the difference between an anchoring villus and a floating villus?
Anchoring villi connect to the decidua of the maternal uterus. Floating villi dangle off of the anchoring to bolster fluid contact.
There are two umbilical ___________ and one umbilical _________.
arteries; veins
The umbilical arteries carry deoxygenated blood from the fetus to the ___________ of the placenta.
capillary network within the tertiary villi
The term placenta is roughly _______ the weight of the term fetus.
1/6
What drugs can cause oligohydramnios?
Those that decrease GFR: COX inhibitors and ACE inhibitors
The trophoblasts invade up to the _____________ of the uterus.
most superficial 1/3
Note: the cytotrophoblasts invade the spiral arteries.
hCG peaks around __________.
10 weeks
Women with elevated hCGs may have _____________.
choriocarcinoma (if extremely elevated) or a baby with trisomy 21 (if moderately elevated)
What does hPL do?
Human placental lactogen makes the maternal system switch to fatty acid metabolism and increases insulin resistance to provide sugar to the fetus.
what maintains the corpus luteum and progesterone production until the placenta takes over?
hCG until week 8
what regulated cytotrophoblast differentiation into syncytiotrophoblasts?
hCG
does estrogen production require both maternal and fetal placental tissue?
yes, estrogen synthesis intermediates are shuttled back and forth across the placenta because each part has needed enzymes that the other part lacks.
- placenta lacks P450c17 and 16-a-hydroxylase
- fetus lacks P450 aromatase and 3-B-hydroxysteroid dehydrogenase
