Week 3 Placenta Lectures Flashcards
Leptin inhibits _________.
Insulin
How does the placenta’s structure support its function?
Large surface area with a thin intrahaemal membrane separating circulations
The maternal surface of the placenta is 15-20 _____. The fetal is a ______ covered by amniotic membrane and vessels converging towards the _____.
cotelydons; chorionic plate; umbilical cord
How does “hemomonochorial” describe the human placenta?
One layer of trophoblast cells between layers
What do trophoblast cells come from?
As projections of the blastocyst they allow implementation in the uterine wall. They then differentiate into syncytio-trophoblast cells and cytotrophoblast cells.
Which cells form primary villi?
Cytotrophoblasts while syncytiotrophoblasts connect to maternal sinusoids.
How do the chorionic villi develop?
Vasculogenesis and Angiogenesis. Angioblasts differentiate to form capillary like structures. Then sprouting, branching, and elongation.
What is the purpose of decidualization?
Mesenchymal-epithelial transition helps to lower stiffness, expand organelles, and increase lipid/glycogen storage. NK cells come in to regulate the uterine invasion process.
What is the path of utero-placental circulation?
Low resistance spiral arteries (formed by extravillous sy-trophoblat cells) enter intervillous space, blood leaves then through endometrial veins going across the decidua.
How does glucose get transported to the fetus?
Facilitated diffusion along a concentration gradient through GLUT transporters (GLUT1 is abundant expressed)
How do amino acids come across the placenta?
Active transport, as [] is much higher on the fetal side. There are >15 transporters including System A (Na+ dependent for small, neutral AA’s and stimulated by insulin, leptin, IL6, IGF1) and System L (Na+ independent for large AA’s, stimulated by glucose or insulin.
How do essential fatty acids move across the placenta?
TG lipase breaks maternal triglyceride to FFA’s which use passive or facilitated diffusion.
How is progesterone formed in the placenta and what all can it signal for?
STB and CTB synthesize P4 from cholesterol. It works to maintain quiescence in the myometrium before functional withdrawal. Also, appetite stimulant, and prevents mammary glands from activating before birth
What is the role of estriol?
Estriol is produced by the placenta from DHEA, regulated by fetal adrenal gland. Important for endometrial cell proliferation and mammary gland development.
What does lactogen do?
Promotes fetal growth by inducing lipolysis to FFA’s, maternal insulin resistance to increase fetal availability, fat deposition, appetite stimulant, protein synthesis, and milk production.
How does PGH support fetal growth?
Secreted by STB cells, stimulates glycogenesis, lipolysis, and anabolism in maternal organs. Promotes insulin resistance in the mom.
Why does leptin increase along gestation?
To combat resistance induced by all the other hormones.
How does leptin influence fetal growth?
Alters nutrient transporter activity, promotes angiogenesis and very important pathways. Levels are super high in complicated pregnancies.
What does placental dysfunction usually refer to?
Compromised invasion of trophoblast cells to spiral arteries —> poor remodeling —> reduction in nutrient/oxygen delivery —> higher risk of preeclampsia, etc.
Altered glucose transport plays a role in fetal growth restriction (T/F).
True, hypoglycemia is implicated but no reduced uptake or expression of GLUT1. Late-term FGR does show more GLUT3 expression and increased consumption by the placenta.
How does placental dysfunction impact amino acid and fatty acid transporters?
Reduced expression/activity of System A and L transporters, less AA in umbilical cord blood. Reduced LPL activity means less fatty acid transport.
Name the nutrient-sensing signaling pathway in the placenta.
mTOR, a serine/threonine kinase that controls cell growth and metabolism in response to maternal metabolic hormones and local nutrient levels.
What are two oxygen sensors in placenta?
mTOR (reduced activity in hypoxic situations) and HIF (increased angiogenesis)
How does Zika impact fatty acid transport?
Hijack transport molecule to transform to virus factories, lack of essential lipids + massive inflammation
