Female Reproductive Function Flashcards
what are the three phases of the ovarian cycle?
follicular, ovulatory and luteal
what are the two functions of the ovaries?
to produce ova and hormones
describe the follicular phase and trigger.
FSH stimulates development of follicles
describe the ovulatory phase and trigger
LH surge causes rupture of one of the follicles
describe the luteal phase
LH converts the ruptured follicle to the corpus luteum
what happens to the corpus luteum if fertilization does not occur?
it degenerates into a corpus albicans
what do primordial follicles consist of and when are they developed?
they contain a primary oocyte and are formed by 6 months of age
what three cells are contained within a follicle?
ovum, thecal and granulosa cells
what is the final stage of a follicle before release?
the graafian follicle
what are the three phases of the endometrium?
proliferative, secretory and menstrual
what does estradiol do to the endometrium and what ovulatory phase does this correspond with?
promotes proliferative phase of the endometrium increasing thickness
follicular phase
what phase corresponds with the variability of menstrual cycle length?
the proliferative phase can vary in length
what does progesterone do in the uterus and what ovulatory phase does this correspond with?
triggers the secretory phase
luteal phase
what is the secretory phase in the endometrium?
accumulation of glycogen, increased glandular secretion and increased vascularity in the endometrium
what mediates the menstrual phase? describe it.
prostaglandin
vasoconstriction of arteries causes local ischemia
what part of the ovarian cycle corresponds with the menstrual phase?
regression of the corpus luteum
describe the positive feedback on the ovarian cycle.
estradiol reaches high levels in late follicular phase causing LH and FSH release
describe the negative feedback on the ovarian cycle.
early follicular phase: estrogen has negative feedback
luteal phase: estradiol, progesterone and inhibin produced by the corpus luteum decrease gonadotropin release
which axis is responsible for the ovarian cycle?
the hypothalamic-pituitary- ovarian axis
GnRH-> LH and FSH-> androgen, progestin andestrogens
describe the characteristics of the release of GnRH and LH
they are pulsatile and increase in amplitude during the follicular phase
what causes the increase in amplitude of LH in the follicular phase?
high circulating estrogen sensitizes the gonadotrophs of the anterior pituitary to stimulation by GnRH
where is GnRH secreted?
from small neurons in the arcuate nucleus and preoptic area of the hypothalamus
what are the two effects of GnRH?
to increase secretion of FSH in the follicular phase and LH during the luteal phase
what cells does FSH bind to and what does it cause?
granulosa cells
stimulates transcription of enzymes, activins and inhibins
what cells does LH bind to and what does it cause?
theca cells (granulosa cells also have receptors) stimulates synthesis of progestins and androgens
what do granulosa cells do to androgens secreted by theca cells?
they turn them into estrogens
where do actins and inhibins act? what do they do?
on the anterior pituitary
activate/inhibit gonadotropin release
where do estrogens and progestins work as feedback?
on both the hypothalamus and the anterior pituitary
describe the signaling pathway of GnRH
binds to GPCR and triggers the IP3/DAG signaling pathway
DAG->PKC-> gene transcription alteration
IP3-> intracellular calcium release-> exocytosis of gonadotropin
what types of hormones are estradiol and progesterone? how do they travel in the blood?
steroid hormones
bound to sex hormone binding globulins
what 6 tissues do female gonadotropins act upon?
breast, bone, vagina, cervix, fallopian tubes and uterus
how are estrogen and progesterone removed from the body?
estrogen: inactivated in liver by conjugation and excreted in urine
progesterone: degraded to other steroids in liver and urinated
what are the major products of the follicle and corpus luteum?
estradiol (follicle) and progestins (corpus luteum) although there is still estradiol production
what enzyme does the theca cell lack?
aromatase
what hormone promotes the conversion of cholesterol to androstenedione? the conversion of androstenedione to estradiol?
LH
FSH
which cells produce progesterone?
both granulosa and theca cells
which cell converts progesterone to 17alpha-OH progesterone?
theca cell (granulosa cell does not contain the enzyme)
what are 4 effects of estrogens?
proliferation of the uterus and development of endometrial glands, development of fallopian tube mucosa, stimulation of bone growth by inhibiting osteoclasts, and increase subcutaneous fat deposition
what are three effects of progesterone?
secretory changes in uterine endometrium, decreasing uterine contractions and increased fallopian tube secretions
what is thelarche? what are the roles of estrogen and progesterone?
when breast development occurs
estrogens- deposition of fat, stromal tissue development and ductile growth in breasts
progesterone- promotes development of lobules and alveoli
what is adrenarche?
increased secretion of adrenal androgens
what is menarche?
when the menstrual cycles begin
what about the hypothalamus-pituitary-ovarian axis changes at puberty? what causes the development of secondary sex characteristics?
the link that activates the hypothalamus
pulsatile secretion of GnRH occurs at the beginning
production of steroid hormones causes transition
what inhibits the release of gonadotropins before puberty?
the negative feedback sensitivity is high so low levels of steroid hormones block gonadotropin release
what is the average age of menopause? how many ovarian follicles are left?
51
virtually none
describe the levels of sex steroids and gonadotrophins in menopause.
sex steroid levels decrease and gonadotrophins increase
what physical and mental changes occur in menopause?
vasomotor instibility, hot flashes, night sweats, mood changes, short term memory loss, sleep disturbance, lack of libedo and headaches
what physical changes occur to the female reproductive system in menopause?
atrophy of vaginal epithelium, changes in pH, decrease in secretions, loss of tone, decrease in circulation to vagina and uterus and pelvic relaxation
how does the amount of germ cells in a fetus compare to the follicle number at birth?
about 4 times the amount as a fetus compared to at birth
how many oocytes are ovulated during a lifetime? how many follicles are there at puberty?
about 400
400,000
what causes the decrease in steroid hormone production in menopausal women? how does this effect gonadotropins?
there are no more follicles to produce it
there is no more negative feedback so gonadotropin levels rise
what causes most of the loss of follicle?
atresia of cells throughout the reproductive lifetime
how can a woman’s menopausal status be determined?
with immunoassays of FSH and LH (10-20x more production in menopause)
what is the postmenopausal source of estrogens? how do they compare to estradiol?
muscle and adipose tissue produce esterone derived from androstenedione from the adrenal gland and ovary
15-25% as potent as estradiol
what accounts for the severity of menopausal symptoms?
amount of esterone produced in other tissues because symptoms are a result of estrogen deficiency
why are postmenopausal women more prone to fracture?
because estrogen preserves bone mass
