Female Reproductive Physiology Flashcards
Describe the mechanism of estrogen receptors towards estrogen dependent gene expression
In the nucleus:
- Estradiol binds to receptors
- Receptors change shape and dimerize
- Dimerized complex binds to Estrogen Response Element (DNA section)
- Multiple coactivators recruited including SRC-1 and CBP, histones rearranged etc
- Transcription of estrogen dependent proteins
Receptors can also bind other (non-estrogen) ligands in the nucleus, and thus stop them from binding to their targets, reducing the expression of these protein. SECOND SOURCE of Estrogen-dependent effects
Approximately halfway through the menstrual cycle, what occurs at the ovary?
Dominant follicle ruptures [corpus hemorrhagicum] and egg is released, aka ovulation
Pregnancy is counted from _______ and lasts approximately ________
The date of the last menstrual period, lasts approximately 40 weeks
What are the two major forms of estrogen receptors, and where are they located, respectively?
ER alpha: mostly in female reproductive tract, but also in lung, brain, vasculature
ER beta: prostate or ovaries
All are in the NUCLEUS of these particular cells
First stage of oogenesis converts ____ to _____ and occurs ________.
Primordial oocytes (and follicles) to primary oocytes (and follicles), and occurs during gestation and up to 6 months postpartum.
Oogenesis arrests until puberty at this point
GnRH release from the hypothalamus becomes ______, which distinguishes puberty in both men and women from childhood.
Pulsatile (pulse release approx every 90 minutes)
Mechanism of Fertilization [other than sexy times]
- Sperm binds to zona pellucida on egg, releases contents from the sperm “head” aka acrosome.
- Sperm fuses with ovum plasma membrane -> ZYGOTE
- Zygote floats down to uterus from fallopian tube over 3 day period, all the while replicating its cells
- By now, zygote has become blastocyst and floats for a day choosing spot for implantation
Seconds stage of oogenesis occurs _______ and entails the primary oocytes growing and maturing.
In the follicle…?
70-85 days during the entire female reproductive period (~35-40 years)
Follicles become antral “aka Graafian” follicles (have a fluid-filled cavity adjacent to oocyte called the antrum.)
50% of antral follicles will be retained
{See image}
From where are LH and FSH released?
Anterior Pituitary
The three organs/ parts of the body which form the axis of hormonal control of female reproduction are?
(HPO)
Hypothalamus
Pituitary
Ovary
8 days after ovulatuion, and after implantation, the trophoblast secretes ______ which does ________.
HCG, Human Chorionic Gonadotropin
Binds to LH receptors, enciting the Corpus Luteum to KEEP MAKING PROGESTERONE
HCG is detectable by home pregancy tests
From where is GnRH released?
Hypothalamus
Why do obese women have fewer symptoms of menopause?
Adipose tissue can create some estrogen, lessening the effects of estrogen loss
Two main jobs for the Ovary
Oogenesis
Synthesize and secrete estrogen, progesterone, androgens
In the luteal phase of the menstrual cycle, what is the mainly secreted hormone, and what does it do?
Progesterone
Has an inhibitory effect on FSH and LH
Fertilization must take place within how long of ovulation for pregnancy?
24 hours
Where is oxytocin produced, and what is it responsible for during pregnancy, and then during lactation?
Oxytocin: pOsterior pituitary
Pregnancy: stimulating uterine contractions during labor (can be given exogenously to start labor and to help ensure whole placenta is delivered after baby)
Lactation: Milk ejection in response to suckling
In Menopause, what happens to the three main hormones?
Estrogen declines,
LH and FSH increase
Hormonal and Developmental Milestones of 2nd and 3rd Trimesters
Placenta takes over producing the steroid hormones
Progesterone made from mother
Estrogen made from both mother, placenta, and fetus
LH effect on granulosa cells
induces expression of FSH receptors
Key Milestones of the First Trimester
HCG levels peak at week 9 and then decline as placenta takes over hormone maintenance
Most organs develop
High risk time for chemical (alcohol, drugs, mercury) birth defects
Breast Cancer drugs typically inhibit which enzyme?
Aromatase
The Granulosa Cells convert _____ to ______ via which enzyme
Testosterone to estradiol (estrogen) via aromatase
GE
Residual Elements of the ruptured ovum follicle form the _______________, which is important because it…
Corpus Luteum
Secretes hormones necessary for egg implantation and zygote maintenance- continues to do so until placenta takes over, if there is fertilization. If no fertilization, luteum shrinks to a scar called a corpus albicans
The third stage of ovum development, unlike the other previous stages, is _______ dependent.
gonadotropin
(hormone)
Where is prolactin produced, and what is it responsible for?
Prolactin: ANTERIOR PITUITARY, release inhibited by dopamine from synapses directly (no intermediate hormone mech like others). Less dopamine -> increased prolactin.
Prolactin responsible for milk production in breasts.
First milk that an infant gets (not true milk) is _________, which has a high concentration of ________.
Colostrum
Antibodies
Developmental milestones of puberty (no question, just chart)
Which class of enzymes convert cholesterol into the steroid hormones?
CYPs
Oogenesis is completed by what age in females?
6 months old (approx 2 million oocytes)
Attrition downhill from there
The first day of a menstrual cycle is conventionally marked by
The onset (1st day) of menses
Mechanism of Implantation
- After floating for a day, blastocyst chooses a spot in the uterus (approx 5 days post-fertilization by now)
1a. Must have low estrogen/progesterone ratio to implant at all. LOTS of progesterone - Trophoblast (outer rim of blastocyst) embeds in endometrium, becomes fetal portion of placenta
Hormonal involvement in labor
* Estrogen/Progesterone ratio increases
* E & F prostaglandins increase uterine contractions, softening and dilation of cervix
* Oxytocin receptors upregulated
THECA cells synthesize and secrete 2 hormones- what are they
*Progesterone
*Androstenedione converted to Testosterone
T T
How many oocytes does a woman have at menopause?
Zero
Cause of LH surge which leads to ovulation
Rapid increase in estrogen just prior (unknown mechanism)
FSH general effects on ovum (3)
- Stimulates follicle growth (Follicle Stimulaing Hormone)
- Induces expression of LH receptors on theca cells
- Stimulates expression and activity of aromatase enzyme
Hormonal cue for ovulation
Surge in LH
Except just prior to ovulation, estrogen normally has what effect on LH and FSH?
Mediating, aka negative feedback
Time from breast budding to menarche is about
2 years
Increased prolactin levels from breastfeeding has what effect on fertility?
Lowers fertility by lowering GnRH release
(still possible to get pregnant, but less likely. Common birth control misconception)
Three Phases of the Ovular Menstrual Cycle
Two Phases of the Uterine Menstrual Cycle
*Follicular Phase [Proliferative Phase for uterus]
*Ovulation
*Luteal Phase [Secretory Phase for uterus]
After delivery of the placenta, maternal hormone levels ________, which allows for the production of ______
drop
(placenta was the source of most horomones during pregnancy)
Breastmilk, which, during pregancy, was blocked by estrogen/progesterone blocking oxytocin and prolactin
What pathology can be responsible for prolactin release and how?
Hypothyroidism.
Release of more TRH/TSH (compensatory response to lowered circulating T3/T4 levels) will inhibit dopamine release. Thus, increasing prolactin release.
Basic Anatomy Overview
(no question, just a picture)
Two kinds of progesterone receptors, what are they and how do they differ from the estrogen receptors?
PR-alpha (shorter), PR-beta (longer)
Both kinds are made from the same gene, unlike ERs
