Physiology of pregnancy, parturition, and lactation Flashcards
what does estrogen cause the cervix to do
produce a watery mucus which forms channels to aid passage of sperm through cervix
-also causes contractions of myometrium to help propel sperm up toward oviduct
what does estrogen cause the cervix to do
produce a watery mucus which forms channels to aid passage of sperm through cervix
-also causes contractions of myometrium to help propel sperm up toward oviduct
in vivo sperm must breach 3 barriers during the process of fertilization
1) expanded cumulu
2) zona pellucida
3) plasma membrane of the egg (oolemma)
as the male pronuclei and female pronuclei are pulled together what do they do
they replicate their DNA
what day does fertilization usually occur
day 15 or 16 of the menstrual cycle
how does the cavity inside the morula form
active transport of Na+ into morula and osmosis of water = blastocyst
before the embryo implants in the endometrium where does the embryo get its nutrients
from uterine secretions
the presence and action of ___ may determine extent of implantation window and what are they
what enhances
what inhibits
pinopods
- enhanced by progesterone inhibited by estrogens
- endocytose macromolecules and uterine fluid in lumen of uterus
- may allow embryo and uterine epithelium to approximate one another more closely
how does blastocyst avoid rejection by maternal cellular immune system
- release immunosuppressive agents
- releases hCG which is an immunosuppressant and sustains CL
the ___ of the blastocyst secrete ___ that digest the outer-lying zona pellucida
trophoblasts
proteases
-the blastocyst now has “hatched” and can attach to uterine wall
which layer of trophoblast is rapidly proliferating
cytotrophoblast
in vivo sperm must breach 3 barriers during the process of fertilization
1) expanded cumulu
2) zona pellucida
3) plasma membrane of the egg (oolemma)
as the male pronuclei and female pronuclei are pulled together what do they do
they replicate their DNA
what day does fertilization usually occur
day 15 or 16 of the menstrual cycle
how does the cavity inside the morula form
active transport of Na+ into morula and osmosis of water = blastocyst
before the embryo implants in the endometrium where does the embryo get its nutrients
from uterine secretions
the presence and action of ___ may determine extent of implantation window and what are they
what enhances
what inhibits
pinopods
- enhanced by progesterone inhibited by estrogens
- endocytose macromolecules and uterine fluid in lumen of uterus
- may allow embryo and uterine epithelium to approximate one another more closely
how does blastocyst avoid rejection by maternal cellular immune system
- release immunosuppressive agents
- releases hCG which is an immunosuppressant and sustains CL
the ___ of the blastocyst secrete ___ that digest the outer-lying zona pellucida
trophoblasts
proteases
-the blastocyst now has “hatched” and can attach to uterine wall
which layer of trophoblast is rapidly proliferating
cytotrophoblast
syncytiotrophoblast adhesive, invasive and endocrine functions
adhesive: has cadherins and integrins that bind uterine surface epithelia
- invasive: secrete mettaloproteases and hydrolytic enzymes
- endocrine: secrete hCG and progesterone
how does hatching occur
blastocyst secrete factor that converts plasminogen from the uterine cavity to plasmin which is a lytic factor that can break down ZP
what is the first stage in implantation
what protein involved
apposition: earliest contact between blastocyst wall, trophoectoderm and endometrial epithelium
- MUC1 might be involved in apposition, a transmembrane glycoprotein at apiclal surface of endometrial epithelial cells during windown of implantation
what is the second stage of implantation
adhesion: tropoblast attach to uterine epithelium through microvilli of trophoblast
- integrin ligand receptor interactions
- this may dislodge decidual cells from connection to underlying basal lamina, which enables blastocyst to perform invasion
last stage of implantation
invasion: blastocyst attaches to endometrial epithelium, trophoblastic cells rapidly proliferate and diff into inner cytotroph and outer syncytio
- protrusions from syncytiotrohp extend among uterine epithelial cells
- secrete TNF-a which interferes with cadherins and B-catenin
- secrete hCG which is autocrine growth factor for blastocyst
- secrete metalloproteases and serine proteases to degrade ECM
site of penetration of syncytiotroph
uterine stromal cells become polyhedral and full of lipids and glycogen (decidual cells)
- blastocyst superficially implants in zona compacta
- syncyt invade blood supply of mom
the mature placenta is composed of what 3 major structures
chorionic villi, intervillous space, and decidua basalis
___ arteries from the mother empty into ___ which drained by maternal veins
spiral, intervillous space
fetal blood flow
umbilical arteries carry deoxygenated blood away from fetus
-single umbilical vein brings O2 and nutrients to fetus
2 functions of amniotic fluid
mechanical buffer protecting fetus from external insults
-fetus excretes waste products through here
how does fetus not suffer from lack of decreased O2 coming in
fetal Hb has higher affinity for O2
- more hemoglobin
- bohr effect
- high cardiac output of fetus
what goes from fetus to maternal circulation
Water, Urea and waste, CO2, hormones
what goes from mother circulation to fetus
No Homo VIDEO
nutrients hormones, viruses, IgG, drugs, electrolytes (h20), O2
hCG and progesterone
maintains high level of luteal derived progesterone production during first 10 weeks of gestation
what causes morning sickiness
rapid increase in hCG
function of hPL
produced in syncytiotrohoblast
- antagonistic action to insulin
- increases glucose availability
- increases lipolytic actions to help mother shift to use of free fatty acids for energy
what enzmes do syncytiotrophoblast express in high levels
also what receptors
- desmolase
- 3B-HSD
- lack 17-a hydroxylase and 17,20 lyase
- also have LDL receptors
is progesterone production of placenta regulated or unregulated?
unregulated
-placenta will produce as much progesterone as supply of cholesterol and levels of cholesterol desmolase and 3B-HSD will allow
___ stimulates secretion from uterine glands, which provides nutrients to the embryo
progesterone
___ inhibits myometrial contraction and prevents release of paracrine factors that lead to menstruation
progesterone
uterine endometrium well vascularized at time of implantation signif
spiral arteries extend to basal lamina where they can capture hCG, transport to ovary, and rescue the corpus luteum
-blood supply also important for efficient delivery of progesterone to endometrium
what takes over for the CL secreting progesterone and estrogen and when
placenta, by 8 weeks gestation
-cannot do it alone, requires assistance of both mother and fetus
what is the major estrogen during pregnancy
estriol
what enzymes does the mother have
17-B HSD
what enzymes does the placenta have
3B-HSD
17B-HSD
aromatase
what enzymes does the fetal adrenal glands have
17a-hydroxylase
17,20 desmolase
16a-hydroxylase
since the fetus lacks ____ enzyme it never makes anything past ____ and ____ in the liver
DHEA and 16a-hydroxy-DHEA
the placenta is a massive sink for ___ that the fetus does synthesize preventing ____
weak androgens, masculinization of female fetuses
the fetus conjugates steroid intermediates to ___ which ___ biological activity and which intermediates
sulfate which decreases actvity
- pregnenolone
- DHEA and 16-OH-DHEA
maternal cardiac output and blood volume increase during pregnancy
blood volume increase during 1st trimester
- rapi increase during 2nd trimester
- lower rise at 3rd trimester
- plateau during last several weeks of pregnancy
what is the main reason for increase in blood volume in mother during pregnancy
increase in plasma volume through increased aldosterone
-results in increase in: HR, SV, and CO
MAP during pregnancy
despite large increase in plasma volume, MAP decreases during midpregnancy then rises during 3rd tirmester
-reason could be decrease in peripheral vascular resistance from vasodilation of progesterone and estradiol
cardiac output during pregnancy
increases by 35-40% during 1st trimester
- only slight increase during 2nd and 3rd
- reflected by increase in SV and HR
increased levels of progesterone during prenancy ___ alveolar resp and why
increases
- increases tidal volume and therefore alveolar ventilation
- direct stimulatory effect of progesterone and lesser extent estrogen on medullary respiratory centers
GI tract changes during pregnancy
prolonged gastric emptying time
- decreased gastroesophageal tone–>acid refulx
- decreased colonic motility—>constipation
- increase in demand protein, iron, folic acid
stage 0 of labor
uterine tranquility and refractoriness to contraction
stage 1 of labor
uterine awakening, initiation of parturition, extending to complete cervical dilation
-increase # of gap junctions btwn myometrial cells, increase in # oxytocin receptors
stage 2 of labor
active labor, complete cervical dilation to delivery of newborn
stage 3 of labor
from delivery of fetus to expulsio of placenta and final uterine contraction
braxton hicks contractions
most of pregnancy, uterus undergoes periodic episodes of weak slow ryhtmic contractions
- become stronger during end of pregnacny
- become labor contractions
- positive feedback by baby head stretching uterus
increased uterine excitability due to
progressive hormone changes
progressive mechanical changes
estrogen stimulates the synthesis of ____ receptors
oxytocin
prostaglandins in parturition synthesis stimulated by what
and which ones specifically
estrogen and oxytocin in uterine cells
- uterine stretch
- PGF2a, PGE2
stretch of cervix and oxytocin
increases oxytocin release (ferguson reflex)
what plays the key role in initiation of labor
prostaglandins not oxytocin, oxytocin just sustains labor with powerful uterine contractions
oxytocin after fetus expelled
oxytocin levels stay high during 3rd stage of labor after fetus out bc it constricts uterine blood vessels at site where placenta use to be, thus promoting blood coag
-levels unchanged after delivery
what causes and increase in oxytocin receptors during parturition
estrogen
role of relaxin
produced by CL, placenta, and decidua
- keeps uterus quiescent during pregnacny
- production and release during labor may soften and dilate cervix
fetal hormones on the uterus
oxytocin: excite uterus
cortisol: stimulate uterus
prostaglandins: increase intensity uterine contractions
braxton hicks contractions
most of pregnancy, uterus undergoes periodic episodes of weak slow ryhtmic contractions
- become stronger during end of pregnacny
- become labor contractions
- positive feedback by baby head stretching uterus
positive feedback preg
first: uterine contractions stimulate prostaglandin release = more intense uterine contractions
second: contractions cause cervix to stretch = release oxytocin–> oxytocin causes more contraction, these contractions become self-perpetuating
delivery phases
dilation and effacement
descent and expulsion
expulsion of placenta
prolonged labor and causes
labor lasting more than 18-24 hours
-poor uterine ontractions, baby’s position or size being abnormal, isues with pelvis or birth canal
obstructed labor or labor dystocia
baby cannot exit pelvis bc it is physically blocked
- can result in baby death
- need to do C section
preterm labor time
labor begins before 37th week of pregnany
ruptured uterus
integrity of myometrial wal is breached
-signs: abdominal pain and vaginal bleeding, deterioration of the fetal heart rate, loss of fetal station on manual vaginal exam
preeclampsia
after week 20 of pregnacny
- high BP signs of damage to another organ system, often the kidneys
- protein in urine, generalized edema
- disease of placenta may be involved
- limited blood supply to uterine arteries = ischemia and endothelial damage with release of cytokines
during pregnancy which hormones lead to full development of breasts
prolactin and hCS
-also high levels of estrogen and progesterone
mammogenic hormones
promote proliferation of alveolar and duct cells
lactogenic hormones
promote initiation of milk production by alveolar cells
galactokinetic hormones
promote contraction of myoepithelial cells = milk ejections
galactopoietic hormones
maintain milk production after it has been established
what milk proteins are synthesized by secretory pathway
lactalbumin and casein
-Pi and Ca2+ added and secreted
transcellular endocytosis and exocytosis alveoli secretion
IgA, endocytosed on basal side, exocytozied into lumen
lipid pathway
lipid droplets going in
transcelular spathway
salt and water transport
paracellular path
salt and water and leukocytes
prolactin cannot stimulate milk production during pregnancy bc of what
high estrogen and progesterone levels
what is colostrum
thin, yellowish milk-like substance secreted first few days after parturition, contains high concentration of Igs
prolactin increases what kind of effects on breasets
mammogenic, lactogenic, galactopoietic
what is the most powerful physiological stimulus for prolactin release
suckling
-inhibits hypothalamic dopaminergic neurons
prolactin feedback with GnRH
decrease GnRH and FSH and LH
___ can also enhance milk ejection by stimulating myoepithelial cells
oxytocin
-galactokinetic effect
4 effects of suckling on hormone release
1) suckling stimuli activates afferent neural pathway from breast to spinal cord then to hypothal
2) dopamine relaese (PIF) inhibited
3) spinal cord neurons stimulate production and release of oxytocin from posterior pituit
4) spinal cord neurons inhibit arcuate and preoptic area of hypothalamus cuasing fall in GnRH production
- decrease LH and FSH, inhibits ovarian cycle
