206, 207 Female Endo Flashcards
(26 cards)
Where are GnRH neurons located?
arcuate nucleus of the medial basal hypothalamus
Where are LH and FSH secreted?
anterior pituitary gonadotrophs
What hormones does LH stimulate in the ovary?
androstenedione and testosterone in theca cells
also stimulates progesterone in the corpus luteum (post-ovulation) and inhibin A production
What hormones does FSH stimualte in the ovary?
regulates E2 production by stimulating granulosa cell growth and aromatase activity
stimulates inhibin B production
How does the uterine lining change in response to estrogen and progesterone?
sheds in response to withdrawal of estrogen and progesterone (menses)
regenerates in response to estrogen
Which tissues have aromatase activity?
granulosa cells, adipose tissue, breast, and CNS
Hepatic SHBG production is increased by ___________ and decreased by ___________.
Hepatic SHBG production is increased by estrogen and thyroid hormone and decreased by androgens, obesity, and insulin.
What is the function of inhibin A in the ovary? Inhibin B?
Inhibin A: secreted in granulosa/theca cells of the dominant follicle and the corpus luteum
Inhibin B: secreted by granulosa cells of small antral follicles, increases in response to FSH stimulation
What is the function of activin?
stimulates FSH release, often bound to follistatin (inhibitor)
What is the funciton of follistatin?
inhibits activin, inhibits follicular growth
Fast GnRH pulse frequency selectively increases ______ release; slow GnRH pulse frequency selectively increases ______ release.
Fast GnRH pulse frequency selectively increases LH release; slow GnRH pulse frequency selectively increases FSH release.
What is the function of positive E2 feedback on the ovary/follicle?
positive E2 feedback triggers the LH surge and ovulation
What is menarche vs. adrenarche?
adrenarche is the development of pubic and axillary hair (uncoupled from gonadarche)
menarche is the development of menstruation
adrenarche occurs between age 6-8 (before puberty), menarche occurs at around age 12-13 (after breast budding)
What are the major milestones of early follicular phase?
FSH remains high
dominant follicle selected
LH pulse frequency increases, stimulates theca cell T production (leading to FSH induced conversion to E2 in granulosa cells)
inhibin B increases follicular growth
What are the major milestones of mid follicular phase?
increasing GnRH pulse frequency + increasing E2/inhibin B = suppressed FSH release
What are the major milestones of late follicular phase?
increased E2 production triggers LH surge –> induces ovulation of dominant follicle
What are the major milestones of the luteal phase?
post ovulatory follicle forms corpus luteum and secretes progesterone and E2 (slows GnRH pulse frequency –> increased FSH, decreased LH)
increased FSH stimulates follicle recruitment for the next cycle
if no conception, the corpus luteum dies and progesterone is not produced (leading to menses)
What is the difference between estrogen and progesterone action on endometrium?
estrogen: proliferation of stromal and epithelial cells, increased progesterone receptors
progesterone: induces differentiation of proliferative endometrium, prepares endometrium for embryo
What is primary vs. secondary amenorrhea?
primary = no menarche by 15-16 yo (evaluate if no secondary sex characteristics by age 13)
secondary = no menses for 6 months
How is anovulation diagnosed?
appropriately timed P and LH measurements or a lack of increase in basal body temperature
What is hypogonadotropic hypogonadism in women?
anovulation, oligomenorrhea, or amenorrhea with low or inappropriately normal LH/FSH levels
What are some common causes of functional hypothalamic amenorrhea?
weight loss (ex. eating disorder)
exercise
stress
What are the hormonal changes in chronic hyperandrogenic anovulation?
increased frequency of GnRH pulsing leading to increased LH/decreased FSH
leads to theca cell overproduction of androgens and underconversion to estrogen (because of decreased FSH)
What is the assessed with progestin and estrogen challenges?
assesses if source of bleeding is related to androgen insufficiency, estrogen insufficiency, both, or neither
bleeding after progestin = evaluate for secondary amenorrhea
no bleeding after progestin, bleeding after estrogen = hypothalamic amenorrhea or ovarian failure
no bleeding after either = consider anatomic abnormality
