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Average Cycle (in days):
-29.5 days (10-15% of women)
-Most are 25-30 days
-YOUNGER WOMEN TEND TO HAVE LONGER CYCLES THAN OLDER WOMEN
-SPONTANEOUS OVULATORS: occurs every month whether or not they had sex
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Dormitory effect:
- -Women grouped togehter for a long period of time in dormitories tend to have synchronized menstrual cycles
- -College women who have sex often have menstrual cycles that are less variable in length than women who are virgins
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ANIMAL menstrual cycles:
1.Estrous behavior:
2.Monestrus:
3.Induced Ovulation:
4.Light effects:
- 1. Females sexually receptive only around the time of ovulation when estrogen is high
- 2. Mammals that only have 1 time of estrous a year
- 3. Females are continually receptive to males and only ovulate as a result of stimulus from sex
- 4. Rats in light will be in estrous continuously whereas rats in the dark wont be
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Human menstrual cycle:
- *Highly coordinated series of endocrine events that results in ovulation from a single follicle and preparation of uterus to receive embryo
- *Cycle driven by the activity of hypothalamic GnRH pulse generator and surge center
- *LH and FSH induce steroid secretion by the ovaries with structural changes in the ovaries and the uterine tissues
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28 day Menstrual Cycle:
1. First Day
2.Menses
3.Follicular Phase
4.Ovulation
5.Luteal:
- 1.1st day of phase
- 2.lasts 5 days
- 3.day 6-14
- 4.Day 14 (14 days before next mesntruation)
- 5. Day 15-28
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MENSES (Menstrual) Phase: (early follicular phase)
-4-5 days (can be 6)
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Follicular Phase:
- -Rapid growth of ovarian follicles
- -Days 6 to 14
- -Ovarian follicles continue growth that began during the menstrual phase resulting in estradiol production which supports the growth of endometrium
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Ovulation:
- -14 days before next menstruation
- -14 to 28 or 16-30
- -If fertilization doesnt occur the OVUM disintegrates
- -If it does occur then the embryo implants in the uterine lining
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Luteal Phase:
- -15-28
- -Corpus Luteum formed from the wall of the ovulated follicle secretes progesterone and estradiol which prepares the uterus for implantation of the embryo
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MENSTRUAL PHASE (DETAIL):
- -Corpus Luteum of previous cycle disintegrates DRAMATICALLY DECREASES PROGESTERONE AND ESTROGEN which cause the stratum functionalis to disintegrate
- -33-83mL of blood usually lost, but up to 267mL can be lost.
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DAY ONE:
- -FSH,LH, ESTROGEN, and PROGESTERONE are all low
- -small tertiary follicles present
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Day 3:
-FSH, LH , and ESTROGEN moderately elevated
- -PROGESTERONE stays low through menstrual phase
- -Some tertiary follicles now larger
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Days 6-14:
- -Rapid growth of ovarian follicles
- -Ovarian follicles continue growth that began during the menstrual phase resulting in estradiol production which causes growth of the uterine endometrium)
- -Estradiol secreted by developing follicles which causes endometrium to thicken during follicular phase
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Days 10-12:
-FSH causes some teritary follicles to increase in size
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Day 12-13:
- -Estrogen levels progressively rise and peak on these days
- -Leads to POSITIVE FEEDBACK and an increased GnRH which in 2 to 3 days produces LH surge with smaller rise in FSH
- -Small rise in FSH could be because the ovary secreting hormones INHIBIN and FOLLISTATIN inhibit the release of FSH and this counter the stimulatory effect of GnRH
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Day 13:
- -1 Graafian follicle emerges and the rest become atretic
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Day 14:
-Ovulation of ovum from Graafian follicle
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Right before Ovulation:
- -Estrogen levels drop rapidly
- -Graafian follicles SWITCH from delta 5 (estrogen prod) to delta 4(progesterone prod) in response to LH surge
- -Progesterone levels begin to rise just before ovulation
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LH SURGE:
- -induces resumption of meiosis in oocyte in Graafian follicle
- -lasts 36 hours and ovulation occurs 9-12 hours after surge
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Ovulation:
- -MITTELSCHMERZ: pain in abdomen
- -Basal Body temp decreases slightly at ovulation. then rises during luteal phase of cycle
- -Cervical mucus watery and stringy
- -Spinnbarheit: threadability of mucus
- -Fern test: mucus exhibits a fern-like pattern of crystals of sodium and potassium chloride when dried
- -HIGH LH levels in blood
- -HIGH PROGESTERONE levels in blood show in luteal phase and that ovulation has occured
- -PREGNANEDIOL is a breakdown of progesterone that is detected in urine during luteal phase
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Luteal:
- -Last 14 days from ovulation to menstruation
- -Generous production of progesterone and estrogen furing the luteal phase cause the endometrium to become thick and spongy and its glands secrete nutrients that can be used by embryo if there is implantation
- -Secretory Phase
- -corpus luteum is formed from the wall of the follicle that released the ovum
- -Corpus luteum secretes profesterone and estradiol
- -(day 24) the corpus luteum disintegrates and progesterone and estrogen drop rapidly
- -Onset of menstruation
- -High ratio of progesterone to moderate estrogen INHIBITS GnRH which INHIBITS LH and FSH production
- -LH levels are low but still can maintain the function of the corpus luteum
- -INHIBITION of FSH restricts follicular development
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Menstrual cycle follicular Phase Summary:
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