Hormonal Cycle Flashcards
Ages of menarche and menopause
12.5
51
At birth females have 1 million primordial follicles. They oocytes are arrested in _______
prophase of the first meiotic division until menarche
The hypothalamus secretes ________ from the _________ in a ________ manner.
GnRH from the arcuate nucleus in a pulsatile manner (every 70-90 minutes)
GnRH stimulates the ________ to release ________
anterior pituitary to release FHS and LH (gonadotropins)
TSH acts at
thyroid gland
released from ant pit
ACTH acts at
adrenal cortex
released from ant pit
TSH and LH act at
testes and ovaries
released from ant pit
GH acts at
entire body
released from ant pit
PRL (prolactin) acts at
mammary glands
released from ant pit
endorphins act on
pain receptors in brain
released from ant pit
LH stimulates ______, which causes _________
- LH stimulates theca cells of ovary to produce androgens
2. Androgens to to granulosa cell of ovary and are converted to estrogen by aromatase
FSH stimulates _______ which causes ________
- FSH stimulates granulosa cells to convert androgens (coming from the thecal cells) to estrogen by aromatase during the follicular phase of the menstrual cycle
Estradiol (estrogen) has a negative feedback on ______ and a positive feedback on ______
negative fb on GnRH and FSH/LH most of the cycle, but a positive fb on GnRH/FSH/LH for days 12-14 (high estrogen levels during this time)
So basically granulosa cells of ovary produce ______ and theca cells produce _______
estradiol
androgen
Estrogen provides _________ to hypothalamus and anterior pituitary for most of the cycle, but ________ for days 12-14
negative fb for most
positive fb for days 12-14
the positive fb of estrogen is mostly acting on LH
In order for FSH and LH to be released, you need ________
a PULSATILE release of GnRH
LH acts on 2 places in the ovary (and why)
- growing follicle (for ovulation and to produce estrogen, this mid-cycle increase of estrogen will stimulate more LH secretion, positive FB)
- corpus luteum (which secretes progesterone and estrogen after ovulation to inhibit FSH and LH secretion)
Phases of menstrual cycle
follicular phase, ovulation, luteal phase
Day 1 of follicular phase:
- First day of bleeding
- progesterone withdrawal is happening (causes period bleeding)
- Prostaglandins are released–> causes contractions of uterus
- -> ischemic pain (cramping)
- hormones are all at their LOWEST points on day 1
- this causes at DECREASE in the negative feedback, resulting in FSH production
FSH production on day 1 of follicular phase causes
- new follicles to mature
- dominant follicle to be selected
- granulosa cells increase and secrete estradiol
Follicular phase- Estradiol acts at the LH receptors on
theca cells, cause androgen secretion, which are converted to more estradiol by aromatase