menstruation Flashcards
what causes estradiol levels to rise
presence of LH -> testosterone -> androstenedione -> FSH -> FSH receptors -> granulosa cells -> aromatase (FSH dependent) -> estradiol
what causes the increase in LH levels around Day 11
estradiol, positive feedback with LH surge
approximately when does luteinization occur
day 14
-granulosa cells become luteal cells -> led by estradiol -> make LH which makes progesterone
why are progesterone levels so low until day 13? why do they drop around day 25
-dependent on luteinization, hasn’t occurred yet
-corpus luteum dies so progesterone dies off
when do we see low estradiol levels
early follicular, menstrual, late luteal phase
how does increase of estradiol affect AVPV nucleus
-regulates expression of kisspeptin in the AVPV
-estradiol always stimulates AVPV
how does decrease of estradiol affect ARC nucleus
-regulates kisspeptin in the ARC
-estradiol always inhibits ARC
how does ER (estrogen receptor) signaling differ between two populations of AVPV and ARC
-not known
-E2 receptors are the same in AVPV and ARC
what do testicle havers have substantially
a sexually dimorphic nucleus
what is the feedback loop for androgens
always negative
what is the feedback loop for progesterone
always negative
what is the feedback loop for inhibin
always negative for FSH only
how does rapid rise of LH contribute to ovulation
changes in ovary and follicle
what is the function of plasmin and collagenase
responsible for follicular wall thinning
what is the function of prostaglandins
produced during pre-ovulatory gonadotropin surge = contraction of smooth muscle of ovary and constriction of blood vessels locally
where are prostaglandins produced
in smooth muscle; theca externa which also produces prostaglandin receptors
what occurs after ovulation
-granulosa cells invade antrum “luteal” cells
-corpus luteum will degenerate into corpus albicans if there is no pregnancy
how will large quantities of luteal cells affect progesterone and estrogen
-generate lots of progesterone and estrogen (more LH receptors than FSH receptors on luteal cells)
the endometrium thickens from day 7-15. why do we need the endometrium to thicken
where zygote can implant in endometrium, place to gestate
what hormone rises during growing the endometrium
estradiol, grows endometrium
why doesn’t the uterine lining continue to proliferate and thicken after day 14
increase of progesterone, inhibits estrogen which keeps endometrium in tact
what hormone is released from day 13-27
progesterone
what else can estradiol function as
-signals stromal cells to grow and divide
-epithelial cell phenotype becomes more columnar
-produces progesterone receptors
what is progesterone’s purpose
-converting endometrium to a receptive state
-maintaining uterine thickness
-acts as an anti-proliferative in epithelial cells of uterus by blocking mitogenic mediators in cells via transcription factor and blocks estrogen receptors
-secretion of glycoproteins to promote implantation (L-selectin ligand: sLE)
-anti-apoptotic: tissue treated with progesterone significantly less apoptotic cells than tissue treated without progesterone
what would happen to the cells of the endometrium if progesterone was blocked
would divide uncontrollably and die
what happens to the corpus luteum toward the end of the menstrual cycle
-corpus luteum requires elevated LH signaling to survive
-no/little LH = atresia of luteal cells
-no luteal cells = no progesterone d
what does having a drop of progesterone levels mean
-cell death
-endometrial inflammation
-extracellular matrix degradation
-menstruation
