Pregnancy And Parturition Flashcards
What directly determines when mesntruation occurs?
Drop in progesterone.
If fertilization happens, hormones don’t drop and mesntruation doesnt happen
What are the 4 stages of pregnancy?
Initiation (fertilization, implantation, secretion of HCG to rescue c.l.)
Gestation
Parturition
Lactation
Where does fertilization occurs?
Fallopian tube (usually upper third)
When must fertilization occur?
Within 24 hrs of ovulation
Sperm can survive longer 2-5 days so u can get pregnant if u have sex before ovulation
What does the female body do to aid in sperm migration?
Contractions of myometrium
Upward contractions of Fallopian tube muscle
Allurin relased by mature eggs- chemoattractant for sperms to reach egg in ampulla of Fallopian tube **
What is Allurin
The chemoattractant released by mature eggs to help allure the sperm to the egg
What is the optimal site of fertilization?
Ampulla of oviduct
How long after ejaculation will the sperm get into the fertilization site?
30-60 min
What percentage of the ejaculated sperm will make it to the fertilization site?
0.001%
What percentage of ejaculated sperm will even make it into the uterus?
0.1%
What is sperm capacitation?
As soon as the sperm gets into the female, the sperm gets “activated” via altering the surface characteristics of the sperm **
What is required for the sperm to be able to swim through the cervix?
Alkaline pH
Prostate gland secretions help with this, and estrogen helps make the mucus watery to allow them to swim
What causes the myometrial contractions that assist the sperm in their journey though the uterus?
Prostaglandins in the semen
Estrogen-primed tissue
What is the process of sperm capacitation?
While migrating through the female reproductive tract, cholesterol on the outer surface of the sperm is removed, surface proteins are removed, and calcium influx into the spermy worm increases the motility
How do sperm penetrate the corona radiata?
Its easy they just swim right through no special tricks needed.
What happens after sperm penetrate the corona radiata?
They will bind to the ZP3 protein on the zone pellucida
Acrosomal reaction occurs- hydrolysis enzymes are released onto the zone pellucida
What is acrosin?
The hydrolytic enzyme released from sperm that allow it to penetrate the zone pellucida
How many sperm will undergo the acrosomal reaction?
Hundreds of them-it requires a ton of them to degrade the zone pellucida, even though only one sperm will win
What is the zona reaction?
Its a structural change in the zona pellucida that prevents polyspermy.
How does the zona reaction occur?
The second that fertilin* on the sperm’s head binds to an integrin* receptor on the ovum’s membrane, there is a release of cortical granules that degrade ZP3 proteins and harden glycoproteins on the zona pellucida
What signals the ovum to complete its 2nd meiotic division and extrude the 2nd polar body?
Zona Reaction
In the zona reaction _____on the sperm’s head binds to _____ receptor on the ovums membrane
Fertilin
Integrin
Fertilized ovum divides (meiotically/mitotically_
Mitotically
At what stage is a fertilized ovum capable of implantation?
Blastocyst phase (1 week after fertilization)
What days of the mesntrual cycle are the optimal period for implantation? Why?
Days 24-28 due to the action of progesterone
(You want the progesterone to have been working for a few days making the uterus ready to make a baby)
*******WAS IN RED
When will hCG be detectable in the serum?
After implantation is completed (8-11 days after conception)
What rescues the corpus luteum and keeps it from degrading into a corpus albicans when the egg was fertilized?
Placental hCG**WAS IN RED
How many days after ovulation will the blastocyst enter the uterine cavity
4 days
How many days after ovulation will hCG rescale the corpus luteum?
10 days
How long after implantation does it take for the placenta to be well-established and operational
5 weeks after implantation
What prevents immunologic rejection of the fetus?
The placenta
*reason why pregnant woman may be slightly immunocompromised
What are the 3 hormones secreted by the placenta?
hCG- maintains corpus luteum until placenta takes over function in last 2 trimesters
Estrogen- essential for maintaining normal pregancy
Progesterone- essential for normal preganncy
What do we thing is the causative agent of morning sickness?
hCG
What are the actions of hCG?
Same as LH: stimulate the corpus luteum to secrete progesterone and estrogen
When do hCG levels decline?
When the placenta takes over the secretion of estrogen and progesterone (~3 months gestation)
What hormone is detected by most pregnancy tests?
hCG
When do hCG levels peak?
9-12 weeks gestation, then they decline to a stable plateau
How would hCG levels rise if there was an ectopic pregnancy?
They would rise more slowly (no placenta?)
How would hCG levels rise if there was a hydatidiform mole? (A noncancerous tumor that results from an unviable pregnancy)
They would rise slowly continuously (never decline)
What would the rise of hCG levels look like if the fetus died?
Levels would rise normally but then fall with a half life of 24 hrs
How does the placenta make progesterone?
ALL BY ITSELF 😀
has all the enzymes it needs to convert choleserol into progesterone
How does the placenta make estrogen?
In the PLACENTA: cholesterol is converted to pregnenolone
In the FETAL ADRENAL GLAND**: pregnenolone converted to DHEA-Sulfate
In the FETAL LIVER**: DHEA-sulfate is converted into 16-OH-DHEA-sulfate
In the PLACENTA: the 16-OH-DHEA sulfate is converted to Estrogen by sulfatase and aromatase
What stimulates the fetal adrenal gland to convert pregnenolone into DHEA-sulfate?
CRH**
What is the most important estrogen of pregnancy?
Estriol
What hormone levels can we check in the moms urine to see if the fetus is healthy?
Estrogen
Estrogen synthesis is a team effort by the placenta and the fetus
Will the hCG message ever drop before the placenta is ready to take over making estrogen and progesterone?
No
What are the functions of estrogen for pregnancy?
Increased growth of myometrium-muscles for labor💪🏻
development of ductile system of breasts
Stimulates prolactin release
Relax and soften the pelvic ligaments (+relaxin)
Inhibits lactation!!!!**!!*
How does estrogen inhibit lactation’?
Antagonizes prolactin effect on the breast
Inhibits lactalbumin which is required for lactose synthesis
~Everything is READY to lactate, but until the placenta is OUT of the body, she can not lactate!!~
Does progesterone synthesis require cholesterol from the mom’s diet
Yes
What is the source of progesterone during the preganncy?
First 6-12 weeks: corpus luteum
After 12 weeks: placenta
What are the functions of progesterone during preganncy?
Conversion of uterus to secretory gland, readying it for implantation
Formation of cervical plug
Inhibits myometrial contraction
Inhibits prostaglandin synthesis from uterus
Development of alveolus and lobule in breast
Inhibit lactose synthesis
basically helps MAINTAIN pregnancy while estrogen is helping to prepare for delivery
How many weeks after conception will a woman be pregnant for?
38 weeks ***
Not 40, thats when counting from the last mentstual period
What keeps the uterus quiet for the first 2 trimesters?
Inhibitory effects of high levels of progesterone
What happens to the excitability of the uterus as it moves into the 3rd trimester?
Becomes more excitable (Braxton-Hicks contractions)
Where does relaxin come from?
Corpus luteum of pregnancy
Placenta
What does relaxin do?
Relaxes pelvic ligaments
Softens uterine cervix
What are the roles of high estrogen during parturition?
Increases gap junctions between myometrial cells=uterus can contract as a coordinated unit
Increased Oxytocin receptors in myometrium- uterine responds to low levels of oxytocin
Increased prostaglandin production-cervical softening
What causes the increased oxytocin receptors in the myometrium?
Estrogen
Prostaglandins
What could a doctor put on the cervix to soften it more
Prostaglandin gel
What triggers uterine contractions?
Oxytocin receptor concentration reaching a CRITICAL THRESHOLD!!!!!!!!!!*!
Allows the myometrium to respond to normal/low circulating levels of OT.
Then the 1st contraction happens and the levels of OT snowball (positive feedback)
What cases the profound effect of oxytocin on the uterus?
Increased concentration of myometrial oxytocin receptors
Do blood levels of oxytocin rise before labor and delivery?
NO!!! NO!!! NO!!! NO!!! NO!!!!!
The pregnant uterus at term is ____x more sensitive to oxytocin than nonpregnant women
100
What role does cortisol (from the fetus’s adrenal gland) have on the fetus?
Increases pulmonary surfactant**!!*
What is a serum level you could check to see how close to delivery you were?
CRH levels in mom’s blood
CRH levels act as a placental clock for parturition
High levels of CRH are associated with (premature/late) deliveries
Premature
Low levels of CRH are associated with (premature/late) deliveries
Late
What are the 3 theories of why delivery starts?
High estrogen levels cause OT receptors to reach critical threshold
CRH levels in maternal plasma act as a “Placental clock” for timing
Inflammation
What kinds of things can increase inflammation and therefore prostaglandins and Oxytocin receptors, thus causing a premature delivery?
Multiple fetus pregnancies(increased uterine stretching)
Bacterial infections
Allergic reactions
How does inflammation induce labor?
Activation of nuclear factor in the uterus by stretching or by increased macrophages from increased pulmonary surfactant
nuclear factor stimulates production of inflammatory cytokines (IL-8) and prostaglandins which promotes cervical softening
What is a synthetic oxytocin
Pitocin
What are the 3 stages of labor?
Cervical dilation- 24 hours
Delivery of baby- 30-90 min
Delviery of placenta- 15-30 min
What is the longest stage of labor?
Cervical dilation
What is the shortest stage of delivery?
Placenta delivery
What is involution of the uterus?
The uterus shrinking to its progestational size after delivery
Are there contractions during the delivery of the placenta’/
Yes
Why doesnt lactation occur during preganncy?
Inhibition from estrogen and progesterone
What initiates lactation?
Withdrawal of placental steroids at parturition
What sustains lactation?
Suckling - causes release of OT and PL so milk can be let down
What does oxytocin do in lactation
Milk ejection
What does prolactin do in lactation?
Stimulates secretion of more milk
What does prolactin do during gestation?
Stimulates the synthesis of milk enzymes
What do estrogen and progesterone do for lactation during pregancy?
Promote development of mammary glands
Inhibit lactation
What specifically does estrogen do the the breast during pregancy
Stimulates ductal growth
What hormones stimulate the development of lobules and alveoli?
Progesterone
Prolactin
hCS (human chorionic somatomammotropin)
What hormones stimulate milk enzymes?
Prolactin
hCS
What 2 weird hormones also promote lactation?
Insulin and cortisol
How do estrogen and progesterone inhibit lactation during preganncy?
Block the action of prolactin on the breast
Suckling stimulates____
Mechanoreceptors in the nipple
Suckling sustains the production of which 2 hormones?
Oxytocin (posterior pituitary)
Prolactin (anterior pituitary)
What is the pathway that causes suckling to increase oxytocin production?
The Nervous pathway
What can stimulate the nervous pathway to release oxytocin?
Suckling
Infant’s cry or smell **
What can inhibit the nervous pathway and decrease oxytocin production?
Psychological stress
What could happen to a breastfeeding mom if she is way too stressed out?
She could inhibit the nervous pathway and not be able to make oxytocin= can’t eject milk
(Making milk but cant eject it)
What is the major hormone responsible for lactogensis
Prolactin
Where does prolactin come from?
Lactotrophs in the anterior pituitary
What two hormones control the release of prolactin?
Thyrotropin releasing hormone (stimulatory)
Dopamine (inhibitory)
What hormone prevents ovulation during lactation?
Prolactin***
How does prolactin inhibit ovulation during lactation?
Inhibits GnRH release (no FSH or LH)
**
Do lactating women have periods?
No
How long is ovulation suppressed?
As long as lactation continues because prolactin:
Inhibits GnRH secretion
Inhibits the action of GnRH on the pituitary
Antagonizes the action of LH and FSH on ovaries
(Its like triple redundancy)
Can you keep breastfeeding to prevent preganncy
Not recommended
