Menarche, Puberty and Menstrual Disorders Flashcards
How does the HPO axis control ovulation, fertilization and menstruation?
GnRH–> FSH and LH–> estrogen and progesterone
Where is oxytocin secreted and stored?
posterior pituitary
What can the normal ovulatory cycle be divided into?
Follicular phase
–> onset of menstruation to preovulatory surge of LH
Luteal phase
–> LH surge to first day of menses
What initiates an increase in FSH via feedback mechanism after oocyte is expelled?
Decreasing levels of estrogen and progesterone form the corpus luteum
—> decrease when no pregnancy, tell body to increase FSH to stimulate follicular growth and estradiol secretion
What initiates the FSH and LH surge when an oocyte is not fertilized?
Degenerating corpus luteum stimulates increase in FSH that + follicular development and ESTRADIOL secretion
–>increasing estradiol causes FSH and LH surge
How is estradiol formed?
in THECA cell:
cholesterol +via LH
–> androgens (androstenedione and test)
in GRANLUOSA cell:
+ FSH–> estrogens (estradiol)
Why are FSH and LH suppressed via negative feedback?
suppressed by estradiol and progesterone
–>fall if not fertilized, stimulate FSH to secrete more estradiol, cause LH (mostly) and FSH to rise rapidly to ovulate
Where does FSH bind?
granulosa cells
–>produce estrogen
What day is ovulation of the cycle?
14
–> when you would start having intercourse for pregnancy
What enhances hypothalamic release of GnRH and induces midcycle LH surge?
estradiol
When do estradiol levels begin to increase?
low during early follicular development (when menstruating) but rises 1 week before ovulation
When are estrogen levels maxed out during the ovarian cycle?
1 day before LH peak (ovulation)
–>sharp decline, but then maxed out 5-7 days after ovulation, returns to baseline prior to menstruation
Describe progesterone in the ovarian cycle
Very little amount during follicular development
Begins being produced by unruptured graafian follicle prior to ovulation
Peaks 5-7 days after ovulation d/t corpus luteum, returns to baseline prior to menstruation
When is the primordial follicle formed?
oocyte surrounded by precursor granulosa cells
–> 8-10 weeks of fetal development
When does most of the atresia of oogonia occur?
at birth (7 million in womb to 1-2 million)
–> continued atresia until only 400 actually ovulate
What is the corona radiata?
elongated inner cumulus oophorus cells attached to oocyte
–>type of granulosa cells
What initiates sequence of biochemical and structural changes that result in ovulation?
preovulatory LH surge
How does ovulation take place functionally?
Cells on follicular wall surface degenerate–> forms stigma–> basement membrane bulges through stigma–> oocyte expelled into peritoneal cavity
Describe the peaks of estrogen and progesterone during the ovarian cycle
Estrogen: 2 peaks
- -> 1 day prior to ovulation
- -> 5-7 days post ovulation
Progesterone: 1 peak
–> 5-7 days after ovulation d/t corpus luteum secretion
What forms the corpus luteum?
lutenized granulosa cells, theca cells, capillaries, CT
What is the normal functioning lifespan of corpus luteum?
9-10 days
–>replaced by corpus albicans during menses (if no pregnancy)
What test should you order to dx menopause?
FSH
–>if ovaries not responding, GnRH continuously secreting FSH to stimulate follicles for pregnancy
What are the 2 portions of the endometrium?
1: Functionalis (outer)
- -> cyclic changes in morphology during menstrual cycle, sloughed off
- -> spiral As
2: Basalis (inner)
- -> unchanged during cycle, provides stem cells for renewal of functionalis layer
- -> basal As
What are the cyclic changes the functionalis layer of endometrium undergoes?
1: Menstrual
- –> only one can physically see
2: Proliferative/estrogenic
3: Secretory/progestational
