Female Repro Flashcards
What is the major physiologically relevant positive feedback loop?
Oxytocin in Parturition
Which releasing factor hormone is important in the HPO axis?
Gonadotropin-Releasing Hormone (GnRH)
Which trophic hormones are important in the HPO axis?
- Follicle stimulating hormone (FSH)
- Luteinizing hormone (LH)
Which target hormones are important in the HPO axis?
- Estrogens
- Progesterone
- Inhibins
What do androgens produced by Thecal cells (such as estrogen) inhibit?
- GnRH
- LH
- FSH
What does inhibin, secreted by granulosa cells, do?
Inhibits FSH secretion
Which hormone regulates thecal cells?
LH
Which hormones regulate granulosa cells?
LH and FSH (mainly FSH)
What are the three forms of natural estrogen?
- Estradiol (main form during reproductive lifetime)
- Estrone (menopause)
- Estriol (pregnancy)
What time in the menstrual cycle would the female be most fertile?
10-17 days
Estrogen is low during menses so the pituitary secretes ______ and ______ to stimulate growth of _________
FSH and LH, Premordial ovarian follicles
Rising E2 (estradiol) levels cause what hormone to be less prevalent, thus “starving” other follicles?
FSH
Where does FSH and LH accumulate while E2 levels are high?
anterior pituitary
Once estrogen reaches a certain level, what happens to trigger the follicle to rupture?
More GnRH is produced causing a released surge of stored LH and FSH casing follicle rupture (ovulation)
Prior to ovulation is known as the ________ phase. Post ovulation is known as the ________ phase
Follicular, luteal
What levels are high during the luteal phase?
Progesterone produced by corpus lute.
*this inhibits LH and FSH release usually preventing a second ovulation
If no embryo implants, what happens about 14 days later?
- Corpus luteum degenerates to corpus albicans
- shedding of the uterin lining (menses)
What change do granulosa cells undergo following ovulation?
They convert from E2 (estradiol) producing to progesterone producing
What is the most important natural progestin in humans?
Progesterone (basic 21-carbon skeleton)
Which enzyme is key in converting progesterone and other androgens into estrogens?
aromatase
What triggers the hypothalamus to be less sensitive to estrogen and release GnRH to trigger FSH and LH release, causing increased ovarian release of estrogens?
Leptin
At puberty, increased estrogen contributes to bone growth, breast development, pubic hair and the menstrual cycle called what?
menarche
*ovulation does not usually begin with menarche however
In Perimenopause, what feedback loop begins to be lost?
Inhibins inhibiting FSH
FSH is elevated and Estrone (E1) becomes the predominant estrogen in what time period of life?
Menopause
*estrone is formed by amortization of androstenedione in adrenal glands and adipocytes
