Preg and lactation Flashcards
what is the Zona Pellucida
the oocyte membrane which the sperm passes through during fertilization
what hormone is involved in transport of the ovum? when does it occur?
Isthmus of the tube remains contracted for first 3 days after ovulation. Progesterone relaxes the smooth muscle allowing entry into the uterus
why is it important that the fallopian tubes remain contracted for the first 3 days after ovulation
it allows for several stages of cell division forming the blastocyte
what does the blastocyst use for nutrition as it travels to implantation
uterine milk
how long is the blastocyst in the uterus before implantation
1-3days
what is the role of the cytotrophoblasts
the inner layer of the trophoblast that attaches the blastocyst to the endmetrium
what is the role of the syncytiotrophoblast
the outertrophoblast layer that makes the nutrient connection to the endometrium
how does the progesterone (released from the corpus luteum) affect the endometrial cells
it causes the endometrial cells to become swollen and filled with glycogen, proteins, and lipids
After implantation Progesterone causes endometrial cells to swell further forming what?
DECIDUAL CELLS (decidua) (allow for nutrition)
what is the chorion
the layer bt placenta and mother formed by tropoblasts
for how long does the embryo obtain nutrient from the decidua by trophoblastic nutrition? where is the nutritional source after this?
up to 8 wks. Then placental diffusion takes over
what do the umbilical arteries do?
carry deoxygenated blood from fetus to placenta
what do the umbilical veins do?
carry oxygenated blood from placenta to fetus
when is blood pumped by the fetal heart
21 days post fertilization
what ratio can be used to assess fetal development
fetal placental weight ratio (1g placenta feeds 7g fetal tissue)
what are the typical vascular contents in the umbilical cord
2 umbilical arteries, 1 umbilical vein
what 4 factors contribute to the oxygen gradient in the placenta
Maternal 50mmHg: fetal 30mmHg
Fetal hemoglobin= inc affinity
Hemoglobin concentration= 50% greater in fetus
Double Bohr Effect- fetal blood alkaline, moms is acidic
how does glu pass through the placenta
facilitated diffusion in the placenta
how do fatty acids pass through the placenta
diffusion
what secretes hCG
tropoblasts
when is hCG detectable in the blood? when does it peak?
in blood 8-9 days post ovulation (just after implantation), peaks 10-12 wks
inc hCG effect?
Maintains corpus luteum beyond normal lifespan
Stimulates production of progesterone and E2: (keeps FSH low to prevent menstruation)
Endometrium forms decidua-like cells.
hCG receptors in endometrium and myometrium and can inhibit contractions produced by oxytocin
Immunosuppressant
when will the corpus luteum degrade if it is stimulated by hCG
Corpus luteum involutes after 13th to 17th week when placenta takes over hormone production.
where is estradiol initially produced (first 5-6wks following implantation)? where is it produced after?
Initially produced by corpus luteum (first 5-6 wks) stimulated by hCG
Then from placenta syncytial trophoblast cells (from DHEA-S from adrenals of fetus and maternal)