Physio Of Pregnancy, Parturition, Lactation Flashcards
what is the mature placenta composed of?
chorionic villi, intervillous space, decidua basalis
Umbilical vein carries what?
what about the arteries?
O2 rich blood
O2 poor blood
spiral arteries from the mother dump where?
into the intervillous space
what is the placenta the lifeline for for the fetus?
Fetal Gut, lung, and kidney
what is the intervillous space also called?
why is this?
functional capillary
because there’s no capillaries present between the maternal arterioles and venules
factors regulating maternal blood flow?
maternal arterial blood pressure, intra-uterine pressure, pattern of uterine contraction.
the fetus has high affinity for what?
O2
so the hemoglobin of the fetus is higher so it helps facilitate the O2 blood from the mom to the fetus
this happens regardless of the intervillous space having low PO2 from the maternal blood.
other than fetal Hb, what else ensures adequate fetal oxygenation?
high cardiac output to increase the carrying capacity
what crosses the placenta?
waste (urea and creatinine)
lipid soluble steroid hormones
glucose
Endocrine function of the placenta?
syncytiotrophoblasts of the placenta produce several steroid and protein hormones.
**maintain pregnant state of the uterus –> hCG
**stimulation of alveolar growth and maternal breasts
**maternal metabolism
**regulation of development and partuition
first hormone released by syncytiotrophoblasts? when is it highest?
hCG.. the beta subunit is an indication of pregnancy so this is why pregnancy tests work. 10 weeks is highest amount.
when hCG is reduced, what increases?
progesterone from the placenta because we have a shift from having the corpus luteum producing progesterone to the actual placenta producing it… key to maintaining pregnancy
Starts at week 10
Human placental lactose?
Growth Hormone
What are the levels of estrogen in the placenta?
Estradiol is highest, then estriol, then estrone.
in estriol, we have higher levels of this during pregnancy.. outside of pregnancy is estradiol.
hCG has a high affinity for what?
the LH receptor to stimulate it on the corpus luteum to maintain progesterone levels.
Human Placental Lactogen (hPL)
produced by what?
similar to what?
what actions does it have on the body like growth hormone?
produced by syncytiotrophoblast
similar structure to prolactin
**antagonistic action to insulin, contributing to the diabetogenicity of pregnancy*
so it’s like Growth hormone!!
helps shift lipids to the baby for energy
Progesterone?
what produces it for this lecture and what is it required to do?
regulation?
placenta produces a high amount of progesterone, which is required to maintain a quiescent myometrium and a pregnant uterus.
the placenta produces as much progesterone as the cholesterol levels and the levels of desmolase / 3B-HSD will allow.
Estrogen produced by syncytiotrophoblasts?
what comes from the fetus?
major estrogen of pregnancy?
aromatase in the placenta (from syncytiotrophoblasts) facilitates the production of estradiol, estrone, and estrione from the DHEAS (sulforated?) released from the fetal zone.
Estriol
Estrogen
increasing utter-placental blood flow
increase LDL expression in the syncytiotrophoblasts because it needs to sequester cholesterol from the mom to make more estrogenic activities.
induce prostaglandins and oxytocin for parturition
growth and development of breasts
what do syncytiotrophoblasts have that creates a ton of progesterone?
what protein is not required although it’s required by other cells?
a lot of CYP11a and 3B-HSD
StAR protein
also blocks CYP17… which is 17a hydroxylase and the 17,20 desmolase… so it doesn’t go to testosterone
what happens in very late pregnancy to develop the adrenal cortex?
how do we avoid high levels of cortisol in the fetus but
fetal pituitary release ACTH which acts on cholesterol… this portion of the fetus DOES HAVE 17a hydroxylase/17,20 desmolase so it goes to Cortisol
cortisol to cortisone?
11B-HSD type 2
protects fetal adrenal axiss from maternal cortisol
Progesterone does what for uterine motilityy? what about contractions?
REDUCES AND INHIBITS
MAIN estrogen subtype of pregnancy?
ESTRIOL
what does the maternal placental-fetal unit do to overcome the placental limitations?
mother supplies cholesterol as LDL
fetal adrenal glands and liver supply the enzymes lacking in the placenta.
fetus shouldn’t be making any estrogens why
if it did, it would expose itself to high levels of hormones that are needed by the mother, not the fetus.
so no 3B-HSD and aromatase.
what does the fetus do with sulfate?
what does this include?
conjugates stuff to reduce its activity
pregnenalone
DHEA
Progesterone and alveolar ventilation?
increases it
what promotes quiet uterus activity?
progesterone and relaxin
what happens during labor for the myometrium?
increase in gap junctions between myometrial cells and increase the # of oxytocin receptors
0 station?
when the baby’s head is even with ischial spines
what increases the uterine contractility?
what does this do?
estrogen….
technically both estrogen and progesterone increase during pregnancy but estrogen increases even more and progesterone remains constant from 7 month on.
increases oxytocin receptors
what initiales labor?
what physical thing of the uterus increases these?
prostaglandins –> PGF2a and PGE 2 increase motility of the uterus
stretch of the uterus
Ferguson reflex?
stretch of the cervix
what initiates labor?
then once labor is released, what’s released in bursts and what does it do?
prostaglandins
oxytocin, stimulates powerful contractions to sustain labor.
Relaxin does what?
produced by corpus luteum, placenta, and decidua
keeps uterus quiescent during pregnancy
Braxton Hicks contractions?
weak and slow rhythmic contractions throughout pregnancy but they get super strong
preeclampsia?
high blood pressure and signs of damage to another organ system –> often the kidneys
why doesn’t prolactin act and help make milk during pregnancy?
it’s inhibited by high estrogen and progesterone
lactation initiation?
prolactin up
estrogen and progesterone down
suckling
four effects of suckling on hormone release?
1) seeing or hearing the kid suck
2) dopamine release is inhibited (remember that is PIF)
3) spinal cord neurons stimulate the production and release of oxytocin from posterior pituitary
4) spinal cord neurons inhibit the arcuate and prep-tic area of hypothalamus causing fall in GnRH production
suckling reduces GnRH production.. so what’s going to be inhibited?
LH and FSH so inhibiting the ovarian cycle
