The Menstrual Cycle

FSH role in follicular phase

-a rise in serum FSH begins in LATE luteal phase of the PREVIOUS menstrual cycle and continues into the early follicular phase -FSH exerts its influence on follicle growth and development by stimulating granulosa cell mitosis and cytodifferentiation, which initiates development of a group of follicles (the dominant follicle is selected from this group) -induces expression of LH receptors after the dominant follicle is fully differentiated (day 12)

How do you actually define the menstrual cycle? This is NOT synonymous with a period

1st day of a period all the way to the next first day of period

When are menstrual cycles most commonly irregular?

2 years after menarche, and cycles are often anovulatory

Serum levels of estradiol rise from <50pg/ml to ____________ midcycle

200-500

As peak LH levels are reached during the ovulatory phase, what happens to estradiol?

DECREASE

How long is the menstrual phase of the endometrial cycle?

Day 1- 4 or 5 days Marked by disruption and disintegration of the endometrial glands and stroma, leukocyte infiltration, and red blood cell extravasation

After early follicular phase, what happens to FSH and LH levels?

FSH falls but LH rises

what factors affect onset of the menstrual cycle?

diet, nutrition, athletic training, low body fat

When LH peaks, _________ decreases and ________ increases due to luteinization of the granulosa cells (corpus luteum)

estradiol progesterone

Prior to puberty, the HP axis is hypersensitive to negative feedback of low _________ levels. As critical factors are reached (like weight or body fat), the axis becomes LESS sensitive to those low levels.

estrogen

Divergence of FSH and LH levels may be related to which hormone inhibiting release of FSH?

inhibin B

At what phase of the endometrial cycle is there spasm of spiral arteries from lack of fertilization?

ischemic phase

How long is the ovulatory phase?

it extends from 1 day before the LH surge to 1 day after the LH surge

The luteal phase of the ovary corresponds with what phase of the endometrium?

luteal

Which phases of the menstrual cycle are post-ovulatory?

luteal phase of the ovary secretory phase of the endometrium

_________ is the onset of the menstrual period

menarche

The follicular phase of the ovary corresponds with what phase of the endometrium?

menstrual and proliferative

At what part of the endometrial cycle is there loss of estrogen and progesterone support?

menstruation

At what point in the menstrual cycle is the first rise in estradiol?

midcycle

What is the name of the unilateral pelvic pain near the time of ovulation, which can occur either before or after oculation?

mittelschmerz

What hormone of the luteal phase decreases before menses UNLESS the ovum gets fertilized and pregnancy results?

progesterone

What hormone starts to increase about 12 hours BEFORE the LH surge?

progesterone

____________ has strong anti-proliferative effects on the epithelium of the uterus, and thus is able to oppose excessive proliferative effects of estrogens.

progesterone

What happens during the secretory phase of the menstrual cycle?

progesterone secretion by the corpus luteum stimulates the glandular cells to secrete glycogen, mucus, and other substances

What hormones inhibit the synthesis of estrogen and progesterone receptors in target tissues?

progestins

At what part of the endometrial cycle is the endometrium stimulated by estradiol?

proliferative phase

What phase of the endometrial cycle is progesterone most prominent?

secretory phase

What is one of the most important consequences of FSH and LH action on the dominant follicle?

production of estradiol

Prior to menses, there is a series of morphologic changes due to an (increase / decrease) in estrogen and androgen production.

INCREASE

As peak LH levels are reached during the ovulatory phase, what happens to progesterone?

INCREASES

Luteal phase of the menstrual cycle

-begins with the onset of the preovulatory LH surge and ends with the first day of menses -this phase includes the functional lifespan of the corpus luteum, which supports the released ovum by secreting progesterone

The follicle destined to be the dominant follicle secretes the most estrogen, causing increase density of ________ receptors

FSH

What is the dominant follicle?

the only follicle that ovulates

Endometrial cycle (also called uterine cycle)

The 28 days of the menstrual cycle as they apply to the events in the uterus. The endometrial cycle is also known as the uterine cycle, and has the three subphases: menstruation, the proliferative phase, and the secretory phase.

_________ is the presence of pubic hair, and predates menarche by approximately 1-2 years

adrenarche

What hormone from the hypothalamus signals release of FSH, LH, and prolactin from the anterior pituitary?

gonadotropin-releasing hormone

tanner stage 1- female

no breast bud, no pubic hair this is pre-thelarche

Ovulatory phase of the menstrual cycle

the ovum is released from the mature graafian follicle about 36 hours after onset of the preovulatory LH surge

If pregnancy does not occur by day 23 of the menstrual cycle what will happen to the corpus luteum, progesterone, estradiol, and the endometrium?

-corpus luteum will regress -secretion of both estradiol and progesterone will decrease -the endometrium will shed

Action of progesterone on the uterus

-responsible for the secretory transformation of the endometrium, which occurs during the second phase of the ovulatory cycle -proliferative activity of the endometrial glands is reduced, and these glands start producing nourishing substances

What is the length of the typical menstrual cycle?

28 days *may vary from 21-32

What is the average age of menopause?

52

Follicular phase of the menstrual cycle

begins with onset of menses (period day 1) and culminates in the preovulatory LH surge

tanner stage 2- female

breast bud and sparse pubic hair

tanner stage 3- female

breast ptosis begins, more pubic hair but none on thighs teen age first period occurs here

What happens around day 15 when the window for fertilization starts to close?

cervical mucus thickens, corpus luteum degenerates to the corpus albicans (which does not secrete any hormones) so estrogen and progesterone decline and the endometrium sheds UNLESS you are pregnant...in that case the endometrium is maintained by progesterone and you do NOT have a period

What is the proliferative phase of the endometrial cycle?

endometrial GROWTH secondary to estrogenic stimulation by the end of this phase, cellular proliferation and endometrial growth have reached a maximum

About 7 days before the preovulatory LH surge, what two hormones increase until the day before the LH surge?

estradiol and estrone

What hormones stimulate synthesis of both estrogen and progesterone receptors in target tissues?

estrogens

Which phases of the menstrual cycle are pre-ovulatory?

follicular phase of the ovary menstrual and proliferative phase of the endometrium

tanner stage 5- female

fully sexually developed female

tanner stage 4- female

further ptosis of the breast, more pubic hair but still none on thighs 1-2 years after first period

What progesterone levels is indicative of ovulation?

greater than 10 ng/ml at midluteal phase

Before onset of the menstrual period, GnRH is produced in higher amounts, causing increases in LH and to a lesser extent FSH. This leads to _________ feedback of GnRH and an ________ in estrogen levels.

positive increase

What hormone creates in the endometrium the ideal conditions for the implantation and development of the egg (maturation)?

progesterone

What hormone in the luteal phase increases for up to 8 days AFTER the LH surge?

progesterone

LH role in follicular phase

stimulates androgen production by the theca interstitial cells, which enhances follicular atresia (meaning it helps get rid of the follicles that did not ovulate during this menstrual cycle)

Action of estrogens on the uterus

strong proliferative effect on the endometrium, which results in glandular proliferation and a great increase in thickness, as well as development of its vascularization

What hormone increases follicular atresia?

testosterone (androgens)

What do androgens from LH do to the dominant follicle?

the androgens diffuse into the granulosa cells of the dominant follicle and get aromatized to estrogen (FSH induces the aromatase enzyme)

_________ is breast budding, and predates menarche by approximately 2-3 years

thelarche

What happens to LH during the ovulatory phase?

there is a rapid rise in plasma LH in response to the positive estrogen feedback, which leads to ovulation

What happens to FSH and LH levels in the luteal phase?

they decrease

Ovarian cycle

The 28 days of the menstrual cycle as they apply to events in the ovary. The ovarian cycle has three subphases: the follicular phase, ovulation, and the luteal phase.

Feedback loop of FSH and LH

FSH and LH are secreted to start follicle development, they work together to start estrogen secretion. Estrogen then has a NEGATIVE feedback on FSH and stops the secretion of FSH. Increased estrogen at mid cycle causes POSITIVE feedback (increases secretion) of LH. LH surges and ovulation occurs. Corpus luteum forms AFTER ovulation occurs. It secretes estrogen and progesterone. They work together to inhibit the release of FSH and LH through NEGATIVE feedback. Corpus luteum involutes, decreasing estrogen and progesterone, resulting in menstruation.