placental and fetal physiology Flashcards
what causes villious regression, what structure forms as a result
elevated levels of oxidative stress and smooth chorion laeve formation
what is histiotrophic nutrition and why is it important
During early pregnancy the volume of endovascular trophoblast is such that
it plugs the mouths of the spiral arteries, preventing maternal blood flow into
the placenta. The plugging coincides with the period of histiotrophic
nutrition; Histiotroph- nutritional material in spaces between the maternal and fetal
tissues, derived from the maternal endometrium and the uterine glands.
what are function of placenta 4 main ones
• respiratory organ • nutrient transfer • excretion of fetal waste products • hormone synthesis
what happens to placental blood flow during gestation
maternal uterine blood flow increases, fetal umbilical flow increases. shows sharp rise around 30 weeks
where is the site of placental nutrient transport
terminal villus, fetal capillary, bm, synctiotrophoblast inbetween and microvillious membrane on the other side
what drives gaseous diffusion across placenta
concentration gradient
how are lipids transported across placenta
Lipoprotein lipase releases non-esterified fatty acids ((NEFAS) from the triglycerides in lipoproteins (LP). NEFAS are then transported across the trophoblast cells by fatty acids transport proteins (FATP)
State the three systems for amino acid transport across placenta
system a, system l, taurine transporter
how does system a work
System A; Sodium dependent; transports small non –
essential amino acids eg alanine, glycine and serine..
Three isoforms; SNAT1, SNAT2 and SNAT4. SNAT1 major
contributor to system A activity . Regulated by cytokines
and hormones eg Insulin; IL-6 and TNFalpha and Leptin
how does system l work
System L; sodium independent; non essential amino
acids exchanged for essential amino acids eg leucine,
phenylalanine – enabling transport against concentration
gradient. Regulated by mTOR nutrient sensing pathway.
how does taurine transporter work
Taurine transporter- transport taurine against
concentration gradient- cotransport with sodium and
chloride
outline Glucose Transfer across the placental
syncytiotrophoblast cell
cotranported with na , Glucose transfer predominantly by GLUT-1 transporter in the second half of pregnancy ,
