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82 Cards in this Set

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What are the three glands involved in female endocrine secretion?
Hypothalamus, Pituitary, Ovary.
What two hormones does the hypothalamus secrete that are relative to female reproduction?
GnRH and Oxytocin
Where is GnRH released from?
Arcuate n. from the hypothalamus.
What is one stimulator of GnRH release?
Norepinephrine
What inhibits GnRH release?
CRH, Dopamine, Endorphins
What organ does GnRH target?
Anterior Pituitary.
What is the function of GnRH?
Stimulate release of gonadotrophs (FSH/LH) from anterior pituitary.
Where does Oxytocin come from?
Posterior pituitary (produced in the hypothalamus).
What are the roles of Oxytocin in the female?
1) Increase uterine contractions during delivery
2) Milk ejection from mammary
3) Aid in sperm transport
Where is FSH and LH synthesized, stored, and secreted?
Anterior pituitary.
What hormones are released by the ovary?
Estrogen (from follicle)
Progesterone (from corpus luteum)
Androgens
Inhibins and Activins (from gonads-ovaries)
What role do inhibins and activins play?
FSH feedback regulation at the pituitary level.
What does follistatin do? Where is it released from?
It inhibits FSH release from the Pituitary. It is released from the gonads (ovaries).
How does GnRH arrive at the anterior pituitary?
Via the portal circulation.
Where is inhibin produced?
Follicular granulosa cells.
How is inhibin stimulated?
FSH from the pituitary activates inhibin, which will have negative feedback on the pituitary and hypothalamus.
What does inhibin do?
It inhibits the release of FSH from the pituitary.
What neutralizes activin?
Follistatin. Therefore, follistatin will inhibit FSH secretion.
Where are activin and inhibin produced?
Granulosa cells of the follicle.
What does Activin do?
Stimulates the release of FSH.
What is the dominant form of estrogen? What are the other two less significant estrogens?
Estradiol (E2) is dominant. Estrone (E1) and Estriol (E3) are weaker.
What is the precursor of estrogen?
Cholesterol
What regulates the conversion of Cholesterol to Pregnenolone in estrogen synthesis?
LH
What is the rate limiting step of Estrogen synthesis?
Cholesterol --> Pregnenolone
What does the Aromatase Reaction do?
Converts Androgens (Testosterone) to Estradiol (E2).
Where are estradiol and estrone converted to estriol?
Liver
Describe how Estrogens and Progesterone are metabolized.
Converted to water soluble compounds.
How are estradiols transported in circulation?
SHBG (Sex Hormone Binding Globulin)
How is progesterone transported in circulation?
CBG (Corticosteroid Binding Globulin)
How is testosterone transported in circulation?
SHBG
What other protein assists in transporting estradiol, testosterone, and progesterone?
Albumin
What does an ovarian follicle consist of?
One oocyte surrounded by a cluster of granulosa cells.
Name the first function of the ovarian follicle.
Maintain/nurture the oocyte.
Name the second function of the ovarian follicle.
Helps to mature the oocyte and releases it at the appropriate time.
Name the third function of the ovarian follicle.
Prepare vagina and fallopian tubes for fertilization.
Name the fourth function of the ovarian follicle.
Prepare the uterine lining to accept the zygote.
Name the fifth function of the ovarian follicle.
Maintain hormonal support for the fetus until the placenta can do it.
In what stage of meiosis do oogonia ______ freeze in?

When will it resume?
Prophase.


Just prior to ovulation.
What happens to oogonia 6 months after birth?
They all become primary oocytes, some of these primary oocytes will become primordial follicles.
Name the six stages of follicular development in order.
1) Primordial follicle
2) Primary follicle
3) Secondary follicle
4) Graafian follicle
5) Ovulation
6) Corpus Luteum formation
What elements (3) make up the primordial follicle?
One oocyte that is separated from a single layer of squamous follicular cells by the basal lamina.
Where does primordial follicle development begin?
Fetal ovary.
What happens to granulosa cells during the secondary follicle stage?
They form several layers to surround the oocyte.
What role do FSH (and some LH) play in follicle development?
FSH stimulates primary follicles to become secondary follicles.
What is special about the secondary follicle?
Fluid-filled Antrum forms.
What layer surrounds the outer edge of the oocyte?
Zone pellucida.
As the antrum enlarges in the Graafian follicle, what structure begins to develop?
Cumulus oophorous, a stalk-like structure maintaining the oocyte at the edge of the follicle.
What is the rate of growth, a defining feature, of a Graafian cell?
Exponential up to 30 mm in diameter. HUGE.
Why does osmotic pressure in the antral fluid increase in the Graafian follicle?
Mucopolysaccharides begin to break down into smaller particles, raising osmotic pressure.
During what stage does the follicle rupture, releasing the oocyte?
Ovulation.
Where does the oocyte go after ovulation?
To the fallopian tubes via the fimbrae.
What happens to the granulosa and theca cells following ovulation?
Remain in the follicular cavity as part of the corpus luteum.
What does the corpus luteum secrete?
Progesterone and estrogen - during the luteal phase, corpus luteum is the main source.
What is luteolysis?
The regression of the corpus luteum if fertilization does not occur.
What is the corpus albicans?
The remnant of the corpus luteum, which is fibrous scar tissue.
Name the three stages of the menstrual cycle.
Follicular, Ovulatory, Luteal.
What marks the beginning of the early follicular phase?
Onset of menses.
What hormone is increased during menses, the beginning of the follicular phase?
FSH increases, which increases estradiol production.
What effect do estradiol and inhibin have on the developing follicle?
They increase the frequency of LH pulses, also begins to suppress FSH by negative feedback.
What are dominant follicles known for doing in the pre-ovulation stage?
Releasing a lot of estradiol and increasing aromatase activity (which favors exponential growth of the follicle and nourishment of the oocyte).
What initiates the LH surge during ovulation?
Sustained exposure to high levels of estradiol, which synthesizes by positive feedback mechanisms.
How does the effect of estradiol change when secreted in a sustained fashion?
Negative feedback of FSH/LH becomes positive feedback.
What happens to levels of estradiol and progesterone in the early luteal phase?
Estradiol declines and progesterone rises (low estrogen:progesterone ratio) due to LH which drives the corpus luteum.
What role does the corpus luteum play in the luteal phase?
Raises progesterone and estradiol to peak levels.
What effect do high levels of progesterone and estradiol have on the follicle during the late luteal phase?
They suppress FSH and LH, keeping them at their lowest levels, which will prevent menses.
When does luteolysis occur?
During the late luteal phase as progesterone and estrogen levels drop off.
What happens to progesterone and estradiol levels at the end of the luteal phase?
They drop drastically to base levels.
What happens to plasma FSH levels during the menses phase?
Begin a very slow rise now that there is no negative feedback from progesterone and estradiol.
What effect does a high level of estradiol have on the responsiveness of the anterior pituitary to GnRH?
Estradiol makes pituitary more sensitive to GnRH and thus more LH is secreted when bound. Constant exposure to estradiol is shown to change negative feedback of LH to pituitary to positive feedback, thus the LH surge.
What receptors develop on theca cells in the secondary follicle?
LH receptors.
What receptors develop on granulosa cells in the secondary follicle?
FSH receptors.
What new feature is given to the follicle in its secondary phase?
Secretes steroid hormones, like estradiol.
In the secondary follicle, what structure develops in response to FSH and estradiol?
Antrum.
In the Graafian follicle, what three hormones are required for max progesterone production?
FSH, LH, and estradiol.
What cells contain FSH receptors?
Granulosa cells.
What cells contain LH receptors?
Granulosa and theca cells.
What steroids (hormones) are produced by granulosa cells during the Graafian follicle phase?
Progesterone, pregnenolone, estradiol (and aromotase, but no androgens).
What activates aromatase?
FSH. (Aromatase converts androgen to estradiol).
What is estradiol production in the granulosa cell dependent on?
Androgens from theca cells.
How much aromatase is located in theca cells?
Small amounts.
What effect does LH have on theca cells?
Stimulate the production of androgens, which diffuse into the granulosa cells.
Why are theca cells more adept at producing steroid androgens?
The theca cell layers are vascularized and have access to abundant cholesterol. Granulosa cells are not and can only use acetate to produce cholesterol (inefficient).