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Reproductive Biology Questions
Questions
Which two substances inhibit GnRH secretion?
Dopamine and endorphins
What neurotransmitter stimulates GnRH secretion?
Norepinephrine
What is the rate limiting step in LH and FSH production?
GnRH dependent availability of the Beta subunit
What does GnRH require for its biological action on gonadotrophs?
Ca
Describe the GnRH to gonadotroph binding and activation process.
GnRH attaches to a plasma membrane glycoprotein receptor and, after binding Ca,
calmodulin acts to alter the activity of enzymes and cytoskeletal proteins involved in the
process.
What is the rate of release of LH and FSH during the follicular phase?
One pulse per hour
What controls gonadotropin secretion during the follicular phase?
Negative feedback of estradiol
What causes the midcycle gonadotropin (LH) surge?
Positive feedback action of estradiol
What hormone facilitates the release of LH and FSH during the midcycle LH surge?
Progesterone
Does the GnRH pulse frequency increase or decrease during the luteal phase?
Decrease
What hormone(s) are responsible for this?
Progesterone and endogenous opioids
How do you treat Kallman’s Syndrome (1o hypothalamic amenorrhea)?
Exogenous GnRH pulsing
Why is hyperprolactinemia frequently accompanied by hypogonadism or amenorrhea?
Prolactin in excess shuts off pulse generator.
What percentage of germ cells are ovulated in the normal female?
0.1%
About what % of oogonia are produced after a woman enters puberty?
O%
Dose the process of Prophase I to Metaphase II occur before or after the LH surge?
After, it is what initiates the resumption of meiosis.
Which type of follicle can be identified by the presence of Call-Exner bodies?
Graffian or antral follicle
The innermost granulosa cell layer is called the …
corona radiata
What is the most mature stage of a follicle that can be achieved in a pre-pubertal
female?
Pre-antral follicle. The graffian follicle requires FSH and thus a mature hypo-pit-ovarian
axis.
T or F. Folliculogenesis is linked to hormonogenesis in the ovary?
True
The aromatase system that converts androgens to estradiol is LH or FSH induced?
FSH
What is the underlying factor in the elevation of estradiol levels that triggers the LH
surge?
Size & growth of the pre-ovulatory follicle.
What are the 4 oocyte extrusion mechanisms theorized?
1) proteolytic (plasmin)
2) mucification
3) muscular (tension)
4) angiogenic & inflam.
What is the non-pregnant life span of the corpus luteum
14 days
What are the corpus luteum granulosa cells dependent upon for the synthesis of
progesterone?
LDL
T of F. Progesterone is secreted by the corpus luteum in a pulsitile fashion?
True. Reflective of the LH secretion that the corpus luteum is dependent.
What drug do you give for anovulation?
Clomiphene
Does the estrogen:progesterone ratio change before labor, in humans? NO
In sheep? YES
What plays an important role in the stimulation of myometrial activity in humans?
PGs
How do the myometrial cells communicate with one another?
Gap junctions
What stimulates gap junction formation?
Estrogens and PGs
What inhibits gap junction formation?
Progesterone & Indomethacin
What substance acts to decrease intracellular Ca?
cAMP
What acts to increase intracellular Ca?
PGs, oxytocin, IP3, & channels
How does ritodrine act to stop labor?
Activates adenylate cyclase Þ increased cAMP
Name 2 other drugs used to stop labor.
MgSO4 & Nifedipine
Which Disorder do you treat with oxytocin, Prolonged latent or Protraction disorder?
Prolonged latent
What is the most important factor in Fetal Acid-Base Balance?
Uterine-fetal blood flow
What helps cause the pCO2 gradient between fetal and maternal circulations?
Maternal hyperventilation
What is the maternal compensation that occurs in response to the fetal kidneys not being able to handle non-carbonic acids like uric acid?
Increased maternal GFR
T or F. Normal labor is associated with a ß pO2, ß pH, ß HCO3, Ý base deficit, & an Ý pCO2.
True
Which stage of labor ends with complete cervical dilation?
Stage I, active stage
Which stage of labor ends with delivery of the placenta?
Stage III
T or F. To end stage III of labor so you can get back to your repro studying, just pull on the cord until it comes out.
False. Will cause inversion of the uterus and hemorrhage
How many total number of consecutive divisions take place to get to the term fetus?
42
T or F. Mothers tend to have wide variance in their offspring’s birthweight?
False, you silly goose.
What is the limit of caloric intake/day before the weight of the conceptus decreases?
1500 cal/day
T or F. If you are a fetus of a rather large size, your chorionic villi surface area will be inceased proportionally?
True
Is the neonate more sensitive to increased pCO2 or decreased pO2?
pCO2
How does the neonate change his/her minutes ventilation?
Increases the frequency of respiration
What percentage of the combined ventricular output does the placenta normally receive?
40%
What happens to this % after birth?
The lungs get it.
Why is fetal myocardial activity, as far as cardiac output goes, limited?
Aortic and pulmonary arterial pressures are equal
Within how many hours after birth does the ductus arteriosus close?
10-15
The closure of the ductus arteriosus is influenced by what factor?
The increasing pO2
What happens to ventricular output after birth?
LVO - increases 2-3X RVO - increases 1-2X
What are the 5 factors that contribute to the decrease in pulmonary vascular resistance?
1) lung expansion
2) clamping of cord
3) increased pO2
4) decreased pCO2
5) increased pH
When does the fetus experience the most rapid weight gain?
32-38 weeks gestation
What enables the neonate to make the adjustment from anaerobic met. to aerobic met.?
Increase in # of mitochondria
T or F. Neonate brain can utilize ketone bodies.
True
What is substituted for glucose as a metabolic feul in neonates?
Fat
T or F. One problem with babies who are hypoxic is that they can’t oxidize FFA to
maintain blood glucose.
True
What is one condition that you see neonatal hypoglycemia?
Maternal uncontrolled diabetes
What is the most important determinant of fetal blood temperature?
Maternal arterial blood temp.
Non-shivering thermogenesis occurs where?
In brown adipose tissue
What controls thermogenesis in brown adipose tissue?
Sympathetics; NE is neurotransmitter
Who’s thermoregulatory ability is greater, adults or neonates?
Adults. Neonates capacity is ¼ that of the normal adult
What is the range of optimum body temperature in neonates?
36-37.80C
What substance, through increase in cGMP, increases uterine blood flow?
NO
In the first trimester do the uterine cells undergo hyperplasia or hypertrophy?
Hyperplasia
Hyronephrosis of pregnancy is usually limited to which side, right or left?
Right. Sigmoid protects the left.
What are the 3 signs of pre-eclampsia?
Hypertension, proteinuria, edema
What happens to maternal serum creatinine during pregnancy?
Decreases
What happens to creatinine clearance during pregnancy?
Increases (50% increase)
Why does it take more Ang II to get a pressor response in pregnancy?
Increase in vascular refractoriness.
What happens to plasma osmolality during pregnancy?
Decreases to about 290-280 mOsm/L
What heart sounds (S1,S2,S3, and S4) are normal in pregnancy?
S1, S2, and S3
Is ESV increased, decreased, or unchanged during pregnancy?
Unchanged
Is EDV increased, decreased, or unchanged during pregnancy?
Increased in both LV and RV
What change serves to protect the mother from post-partum hemorrhage?
Increase in BV and RBC volume.
What happens to pulse pressure during pregnancy?
Increases due to fall in diastolic BP>fall in systolic.
Why does pulmonary resid. Vol., expir. reserve, and funct. Resid. Cap. all decrease
during pregnancy?
The enlarged uterus compresses the thorax
What happens to pulmonary vital capacity during pregnancy?
unchanged
What changes contribute to the “breathlessness of pregnancy”?
increase in pO2; decrease in pCO2
Which of these four crosses the placenta, TRH, iodine, T3, T4?
TRH and iodine
What other things, besides the placenta, can produce hCG?
1) hydatidiform mole
2) choriocarcinoma
3) fetal tissue
hCG has identical a-subunits with what other 3 hormones?
FSH, LH, TSH
Therefore, we have to measure hCG by measuring which subunit?
b
What hormone serves to stimulate and maintain the corpus luteum?
HCG
What hormones does hCG stimulate the corpus luteum to produce?
Estrogen, progesterone, relaxin
T or F. hCG may act on fetal testis to stimulate testosterone production thus leading to
early masculinization?
True
When is serum hCG levels at its highest level?
8-10 weeks
When can most take home kits detect pregnancy?
2 weeks after conception
When the hCG does not double every 2-4 days starting at 4-5 weeks gestation, what
concerns you?
Ectopic pregnancy
Lab returns hCG levels of > 200,000 mIU/ml, what concerns you?
Hydatidiform mole, choriocarcinoma
Which hormone is responsible for the “diabetogenic effect” of pregnancy?
Human placental lactogen (hPL)
Which placental hormone is highest in level at term?
hPL
hPL has a 96% sequence homology with which hormone?
Human GH
What is the main estrogen of pregnancy, E2 or E3? Of normal menses?
E3 (estratriol); E2
Why does the placenta require a C-19 precursor for estrogen synthesis?
Lacks 17a-hydroxylase
What is the main precursor in estradiol (E2) synthesis?
Dehydroandrosterone sulfate (DS)
Where does the DS come from, and in what percentages?
50% maternal adrenal; 50% fetal adrenals
What is the main precursor in estriol (E3) synthesis?
16-a-hydroxydehydroepiandrosterone - 16a-OH-DS
Where does the 16a-OH-DS come from and in what %?
90% fetal adrenal; 10% maternal liver & adrenal
What is the largest organ of the fetus?
Adrenal
If you had a placental aromatase deficiency, what would you expect?
1) virilization of mother & fetus
2) very tall affected males
What is the most common cause of ß placental estrogen?
ß LDL-cholesterol
What happens to the placental estrogens in fetal erythroblastosis?
Production increases
What three substances are used frwquently to predict fetal abnormalities?
E3, aFP, hCG
What does the trophoblast need for progesterone synthesis?
LDL cholesterol
You have a fetal death. What happens to the levels of progesterone and estrogen?
Estrogen ß, Progesterone unchanged
Why is the progesterone level unchanged when fetal death occurs?
Unaffected because it doesn’t require fetal input. 90% of cholesterol comes from maternal plasma.
When can you perform ultrasound? Any trimester
Chorionic villus sampling? Only in 1st trimester (usually 10-12 weeks)
Maternal serum screening 2nd trimester (usually done at 16-18 weeks)
Amniocentesis? 2nd or 3rd trimester
Fetal Blood sampling? 2nd or 3rd trimester
What is advanced maternal age?
> 35
a-fetoprotein is related to what other plasma protein?
Albumin, both encoded on chromosome 4
What is the most frequent serious fetal malformation in the US? 2nd most common?
CHD, Neural Tube Defects
Why is it most effective to give folic acid before the woman is pregnant?
The neural tube closes at 3-4 weeks, and folic acid has been implicated in reducing the
requency in NTDs.
What causes the MSAFP screening to be normal, even if there is a NTD?
Skin covering the defect.
What is the most common reason for false + MSAFP results?
Underestimation of gest. Age
T or F. NTDs have been associated with maternal diabetes mellitus.
True
What other drugs have been implicated in an increased risk of NTDs?
1- carbamazepine
2- Valproic Acid
3- retinoic acid
In what normal condition would you expect a doubling of MSAFP?
Twin gestations
What is the “lemon sign” (scalloping of the frontal bones) indicative of?
NTD (also banana sign)
If you have… then you have…
Ý AFAFP & Ý AchE NTD
Ý AFAFP & ß AchE some other fetal defect
Ý MSAFP, normal AFAFP, (-) AchE most likely normal
What is the most sensitive marker for Downs syndrome?
HCG
What lab values do you expect in a Downs syndrome fetus?
ß MSAFP, ß E3, Ý hCG
How is MSAFP measured?
In Multiples of the Mean (MOM)
What lab values do you expect in trisomy 18?
ß MSAFP, ß E3, ß hCG
What is the earliest that amniocentesis can be performed?
12 weeks
What are some disadvantages of amniocentesis?
1) takes 14 days to complete routine tests, 2) if preg termination to occur, it’s more complicated.
What is the “big scare” concerning chorionic villus sampling?
Limb reduction defects
T or F. You can test for NTDs with chorionic villus sampling?
False. Have to do MSS.
Which vessel in the fetus has the greatest O2 saturation?
Umbilical vein
Which part of the IVC has the greatest 02 saturation due to streaming?
Left and Dorsal portion
Via which mechanism does the fetus increase its CO the most?
By increasing its HR
The fetal heart is most sensitive to preload or afterload?
Afterload
Which has the greatest influence on fetal HR, parasympathetic or sympathetics? Parasympathetics
What is the vagal response from the stretch receptor input of increased BP?
Slowing of HR & ß CO
On FHR tracings, you notice that the HR is bradycardic. What worries you?
The baby may be hypoxic and have HTN
What usually occurs first in response to fetal “distress” (hypoxia)?
Increase in catecholamines
The ductus arteriosus connects which two structures?
Pulm. A. and aorta
The crista dividens directs flow from what to what?
IVC to the Left Atrium
The crista interveniens directs flow from what to what?
SVC to the Right ventricle
Which has the greatest O2 stauration…
The RA or the LA? LA
The umbilical artery or the umbilical vein? Umbilical vein
IVC or the ductus venosus? Ductus venosus
Umbilical artery or ductus venosus? Ductus venosus
Umbilical vein or ductus venosus? About equal (UV)
Which ventricle receives the blood that will supply the brain and myocardium?
LV
Fetal or Adult…
Which has the greatest CO (ml/min/Kg basis) fetus
Which has the greatest CO (ml/min basis) adult
Which operates at the top of the cardiac function curve? fetus
Which has the greatest pO2 value (normally) adult
What are the 5 fetal responses to “distress” (hypoxemia)
1) increase in catecholamines
2) slowing of HR
3) increase in BP
4) redistribution of CO to heart, brain, adrenal
5) increase in angiotensin II and AVP
What is the AAP recommendation for length of exclusive breastfeeding?
6 months
T or F. Breast feeding decreases the risks of some forms of cancer?
True. (due to hypo-estogenic state)
What is the tail of Spence?
The portion of the breast that extends into the axilla
What germinal layer gives rise to the ducts of the breast?
Ectoderm
What are the ligaments called that connect the breast to the underlying pectoralis? Ligaments of Cooper
2-6% of women have hypermastia. What is it?
Accessory mammary glands
How many milk ducts does the normal nipple contains?
15-25
What kind of secretion takes place in the mammary glands?
Merocrine (protein) and apocrine (fat)
What is responsible for the proliferation of the parenchyma of the breast during the luteal phase?
Estrogen
What hormone is responsible for the initiation of milk secretion?
Progesterone falls and PRL remains high
Why does the fall in progesterone initiate milk secretion?
Progesterone is an inhibitor of lactose synthesis
The maintenance of lactation in Stage III of lactogenesis requires what?
Removal of milk
If a woman chooses not to breast feed, how long are Prolactin levels detectable?
14 days
What is the stimulation for Prolactin release?
Suckling
If a mother is playing with her infant and her shirt becomes wet, which hormone is
responsible?
oxytocin
What is the mechanism of oxytocin on the breast?
Causes myoepithelial cell contraction and thus ejection of milk.
What can inhibit the Milk Ejection Reflex?
Stress and alcohol
What is the rate limiting enzyme in Lactose synthesis?
a-lactalbumin (progesterone inhibits)
Which vitamin has to be supplemented at birth because it is not transferred in mother’s
milk?
Vit K
What gives colostrum its yellow color?
b-carotene
What is the #1 component of mature milk?
Water
What does lactoferrin do?
Inhibits growth of iron dependent GI bacteria; protective for newborn
If you were a baby, which do you think would be easier, breast or bottle?
Bottle
How many times will a normal newborn nurse per day?
8-12
T or F. A law of supply ad demand exists between mother and child?
True
What are some signs that a baby is getting enough milk per feeding?
1) 6-8 wet diapers/day
2) loose stools daily
3) regains birth weight at 2 weeks
4) growth charts
Is Hepatitis B a contraindication for breast-feeding?
No
As menopause approaches, what accounts for the decreased estrogen levels?
Lack of follicle develop.
Why do serum FSH levels increase more than LH as menopause approaches?
1) Decreased inhibin levels
2) increased resistance to follicle recruitment
What is the principle estrogen before menopause and where is it made?
Estradiol, ovary
What is the principle estrogen after menopause and where is it made?
Estrone, adipose tissue
What is the underlying cause in the difficulty of sleeping after menopause?
Low levels of free Tryptophan
What dose estrogen therapy do to help sleep quality?
1) reduces the sleep latency interval
2) increases time in REM sleep
What causes the hot flashes during menopause?
a-adrenergic neurotransmission due to loss of estrogen
T or F. Estrogen supplementation is protective against MI? True
T or F. Estrogen acts to increase HDL and decrease LDL? True
T or F. Estrogen decreases Triglyceride levels? False
T or F. Estrogen decreases lipoprotein A activity? True
T or F. Estrogen increases the relaxing capacity of the arterial wall? True
Liver Ý HDL, ß LDL, ß Cholesterol, Ý TG, Ý Free cholesterol, ß Lipoprotein A
Arterial Wall Ý relaxing capability
Estrogen
Growth Factors
Heart Ý Coronary Blood Flow
Ý Arterial Pulsality Index ionotropic effects
Ý Myocardial Contractility
In post-menopausal osteoporosis, what type of bone suffers the greatest loss?
Trabecular Bone
What does an increase in urinary N-telopeptide tell you?
Bone loss is occuring
Does estrogen prevent bone loss or stimulate bone formation, or both?
Both, with a predominance of born formation in the premenopausal age groups.
What are some side effects of estrogen replacement therapy?
1) endometrial hyperplasia & cancer
2) thromboembolism & stroke
3) HTN
4) Breast Cancer
5) gall bladder dysfunction
Why give progesterone with estrogen?
To decrease the risk of endometrial hyperplasia and cancer.
Will a woman, with a uterus, when on continuous estrogen-progesterone therapy experience bleeding?
20% experience bleeding, usually spotting.
How much Ca per day is needed by the post-menopausal woman?
1200 mg/day for Repro
1500 mg/day for Pharm
