Fertilization, Pregnancy, Parturition, Lactation Flashcards
What are the 4 stages of pregnancy?
initiation
gestation
parturition
lactation
In this phase of pregnancy, the following occurs:
- fertilization
- implantation
- HCG rescue of corpus luteum
Initiation
What is the site of fertilization?
oviduct
At what portion of the oviduct does fertilization typically occur
upper third
When must fertilization occur in referance to ovulation?
within 24 hours of ovulation
How long can sperm survive in the female reproductive tract?
5 days
The following help what reach the oviduct?
- contraction of myometrium
- contraction of oviduct smooth muscle
- Allurin release by mature eggs
sperm migration
this is a chemoattractant for sperm to reach the egg in the ampulla of the oviduct…
allurin
What percent of sperm reach the fertilization site, and in what timeframe?
0.001% within 30-60 minutes
What percent of sperm make it to the uterus?
0.1 %
This occurs when sperm pass through the female reproductive tract. It causes alteration of the surface characteristics of sperm
Capacitation
sperm motility in the cervical canal requires a _____ pH
alkaline
Secretions from what gland in the male reproductive tract elevate the pH?
prostate gland
This hormone makes cervical mucous watery, facilitating sperm motility
estrogen
_______, present in the ejaculate, promotes myometrial contractions
prostaglandins
sperm acquire the ability to fertilize eggs through what process?
capacitation
Sperm capacitation involves what three processes?
cholesterol withdrawal
redistribution of surface proteins
calcium influx
The calcium influx in sperm capacitation has what effect?
increases motility
capacitated sperm can penetrate the ______ and contact the _______ to undergo acrosome reaction
penetrate corona radiata
contact zona pellucida
what does the fertilizing sperm use in order to penetrate the corona radiata?
plasma membrane bound enzymes
the plasma membrane on the head of the sperm binds to which proteins on the zona pellucida?
ZP3 proteins
What triggers the acrosome reaction which allows hydrolytic enzymes to be released onto the zona pellucida?
binding of acrosome to the ZP3 receptors
When the sperm reaches the ovum, what happens?
plasma membrane fusion, DNA injection to the ovum cytoplasm
ZP3 proteins are inactivated and proteins harden the zona pellucida when enzymes from the cortical granules are released. This prevents…
polyspermy (multiple fertilization)
what enzyme is released from the acrosome which allows penetration of the zona pellucida?
acrosin
sperm fusion to the ovum membrane is mediated by ____ on the sperm head and ______ on the ovum membrane
fertilin on sperm
integrin receptor on ovum
This reaction is called…
release of cortical granules containing enzymes for ZP3 degradation and hardening of glycoproteins on zona pellucida…
zona reaction
The zona reaction prevents…
polyspermy
the zona reaction triggers what two events?
- completion of 2nd meiotic division
2. extrusion of 2nd polar body
this process is the formation of the female nucleus and the male pronucleus…
fusion
The fertilized ovum divides via…
mitosis
Within a week, the fertilized ovum differntiates into a ____ which is capable of implantation
blastocyst
Blastocyst impants on endometrial lining via…
enzymes that digest endometrium
Days 20-24 of a regular 28 day cycle are optimal for implantation due to…
progesterone action
When is hCG detectable in maternal serum?
after implantation, 8-11 days after conception
What hormone rescues the corpus luteum?
placental hCG
The placenta is well established and operational how long after implantation?
5 weeks
The placenta performs the functions of what three systems for the fetus?
digestive, respiratory, renal
the placenta acts as a transient endocrine organ that secretes what three pregnancy hormones?
hCG
Estrogen
Progesterone
What two hormones released from the placenta are essential for maintaining a normal pregnancy?
estrogen, progesterone
This hormone released by the placenta maintains the corpus luteum until placenta takes over function in the last two trimesters…
hCG
hCG levels in maternal plasma peak between…
9 and 12 weeks
What allows hCG levels to decline and corpus luteum to regress?
placental secretion of estrogen and progesterone
This hormone has the same actions as LH, stimulates corpus luteum secretion of progesterone and estrogen
hCG
The placenta converts maternal cholesterole to what precursor hormone of progesterone and estriol?
pregenolone
Progenolone in the is taken up by the fetus, where id is converted to _____ by what gland?
converted to DHEA-sulfate by adrenal gland
Fetal DHEA sulfate is converted to what by what fetal organ?
16-OH DHEA Sulfate by fetal liver
Fetal 16-OH-DHEA Sulfate is transported to the placenta, where which enzyme converts it to estriol?
sulfatase aromatase
Pregenolone is converted to what hormone which is sent to both the fetus and the mother?
progesterone
What is the most important estrogen of pregnancy?
estriol
Synthesis of this hormone requires both the fetus and the placenta…
estriol
Levels of which hormone in maternal urine can be used as an index of fetal health?
estriol
This hormone is responsible for developing the ductile system of breasts…
estrogen
This hormone stimulates prolactin release by the anterior pituitary
estrogen
this hormone relaxes and softens pelvic ligaments
estrogen
This hormone inhibits lactation by antagonizing prolactin and inhibiting lactalbumin…
estrogen
In the first 6-12 weeks of pregnancy, progesterone is mainly secreted by…
corpus luteum
after which week does the placenta take over as the major source of progesterone secretion?
week 12
This hormone converts the uterus to a secretory gland making it ready for implantation
progesterone
this hormone is responsible for forming the cervical plug
progesterone
this hormone inhibits myometrial contraction…
progesterone
progesterone does what to prostaglandin synthesis from the uterus?
inhibits it
Progesterone is responsible for the development of what two structures in the breast?
alveolus
lobule
Which hormone inhibits lactose synthesis?
progesterone
During gestation, volume of blood in the mother increases by…
30%
respiratory activity in the mother increases by _____% in gestation
20%
What keeps the uterus quiet during the first 2 trimesters?
inhibitor effects of progesterone
this hormone:
- produced by corpus luteum and placenta
- relaxes pelvic ligaments, softens cervix
- loosens connective tissue between pelvic bones
relaxin
Parturition is made up of what three events?
labor, delivery, birth
Parturition requires what two physiologic changes?
cervical dilation
myometrial contraction
Do we fully understand the factors that trigger increases in uterine contractility/initiation of parturition?
no
Increased estrogen results in increased ____ receptors in the myometrium
oxytocin receptors, increased oxytocin sensitivity
Increased oxytocin sensitivity has what effect on uterine contractions?
increased
What are three roles of high estrogen levels in labor induction?
Uteral gap junctions
OTR and prostaglandin synth
increased gap junctions due to high estrogen levels allows what to occur?
coordinated uterine contraction
enzymatic degradation of collagen fibers due to high estrogen levels contributes to…
cervical ripening
____ must reach a critical mass for labor to begin.
oxytocin receptor concentration
What is responsible for the profound effect of oxytocin at term?
increased myometrial OTRs
Uterine responsiveness to oxytocin is ___x greater at term than in non-pregnant women
100x
What acts as a “placental clock” for parturition?
CRH
High CRH is associated with…
premature delivery
low CRH is associated with…
late delivery
_____ of the placenta secretes CRH to fetal circulation.
fetal portion of placenta
Increased CRH in fetal circulation leads to an increase in what other fetal hormone?
ACTH
Increased fetal ACTH, stimulated by CRH, stimulates release of what 2 hormones from the fetal adrenal cortex?
DHEA and cortisol
DHEA from the fetal adrenal cortex increased the availabity of the placenta to convert DHEA to…
estrogen
Increased fetal _____ stimulates fetal cortisol production
ACTH
increased fetal cortisol due to increased ACTH leads to maturation of what fetal tissue?
lungs
Critial CRH level ensures that when labor begins, the infant is ready for…
life outside womb
activation of what in the uterus is caused by…
- uterine stretching (multiple fetuses)
- incrased production of macrophages due to increased pulmonary surfactant
nuclear factor (NF-kB)
This inflammatory mediator stimulates production of cytokines and prostaglandins which promote what?
NF-kB, promote cervical softening
Bacterial infx
Allergic Reaction
Multiple fetus pregancies
These can all activate what and result in premature labor?
NF-kB
Is the onset of contractions a response to high, low, or normal levels of circulating oxytocin?
normal
Positive-feedback by oxytocin progressively increases until what? (2)
cervical dilation and delivery are complete
What is the pharmacological synthetic form of oxytocin?
pitocin
Stage 1 of labor is characterized by what event, and for how long?
cervical dilation
few hours-24 hours
stage 2 of labor is characterized by what event and for how long?
delivery of baby
30-90 minutes
Stage 3 of labor is characterized by what event and takes how long?
delivery of placenta
15-30 minutes
Delivery of a baby (stage 2) occurs when what is complete?
cervical dilation
After delivery, what happens to the uterus?
shrinks to pregestational size (involution)
Which hormone during gestation stimulates the synthesis of milk enzymes?
prolactin
Lactation doesn’t occur in pregnancy for what reason?
inhibition from estrogen and progesterone
what sustains lactation?
suckling
_____ causes milk ejection while _____ stimulates secretion of more milk
oxytocin = ejection
prolactin = production
What three hormones act to develop the lobules and alveoli in breast tissue?
progesterone
prolactin
hCG
What two hormones stimulate milk enzymes?
prolactin and hCS
Sucking and what two other factors stimulate the nervous pathway of lactation?
infant cry or smell
What stimulus inhibits the nervous pathway of milk ejection?
psychological stress
oxytocin is released from the posterior pituitary in the nervious pathway of lactation, which has what effect on the breast?
contraction of myoepithelial cells surrounding alveoli
Prolactin stimulates what cells leading to increased milk secretion?
alveolar epithelial cells
_____ stimulates prolactin release, while _____ inhibits prolactin release
TRH = stimulatory
DA = inhibitory
Prolactin inhibits GnRH with prevents what?
ovulation
Inhibition of GnRH inhibits the release of what two hormones leading to amenorrhea?
LH and FSH
In non-lactating women, ovulation resumes in ____ weeks postpartum
7-10 weeks
In lactating women, ovulation resumes with _____ months
7 months
For full ovulatory suppression, how often must you breast feed?
regularly
Is breast feeding a method of contraception?
no
