Exam #4: Female Reproductive Physiology II Flashcards Preview

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Flashcards in Exam #4: Female Reproductive Physiology II Deck (33):

Outline steroidal production during the follicular phase. What regulates the production of steroidal hormones during this phase?

- Theca (that surround the follicle with granulosa cells) cells synthesize androstenedione in response to LH
- Androstenedione is converted to estradiol in granulosa cells (enzymes), which is controlled by FSH

*****IT takes BOTH cells, theca & granulosa to make estradiol & BOTH FSH & LH


What is the effect of estrogen production during the follicular phase?

- Negative feedback on the hypothalamus & anterior pituitary (primarily) to keep the levels of LH & FSH relatively low
- Estrogen also causes proliferation of the endometrium


What is the effect of the rise in FSH in mid-follicular phase?

1) Development of the granulosa and theca cells
2) Increase in steroid production
3) Extremely rapid follicle growth


What is the difference between the theca externa and theca interna cells?

Theca externa= capsule of the follicle

Theca interna= hormone producing


In the follicular phase, how many mature follicles actually become ready for ovulation?

Only one dominant or mature follicle actually becomes ready for ovulation, the rest undergo atresia


What causes the atresia of the non-dominant follicles?

Decline in FSH that may be induced by Inhibin B

*****This is how we get just one follicle for ovulation


What happens during the follicular phase in regards to the endometrium?

Prolifeation of the uterine endometrium
- stromal cells
- growth of endometrial glands
- blood vessel development
- mucus secretion

*Note that this is regulated by estrogen


When does estrogen peak?

Just before day 14 i.e. just before ovulation


What is the effect of the estrogen peak?

Positive feedback on HPG axis, which results in a surge of gonadotropin or LH/ FSH


When is there a peak of LH & FSH? What happens?

- Day 14
- Ovulation i.e. rupture of the follicle & release of the oocyte


What is absolutely required for ovulation?

LH surge at Day 14

NO LH = NO ovulation


What happens to progesterone levels after ovulation?

Rise i.e. progesterone levels rise in the Luteal Phase


What effect does progesterone have on basal body temperature?

Increase in basal body temp

****Thus, basal body temperature can be a marker ovulation


What are basal body temperature measurements used for?

Determining if ovulation has occurred i.e. increased basal body temperature is indicative that ovulation has occurred


What is the corpus luteum?

A temporary endocrine gland that secretes estradiol and progesterone; this the remnant of the rupture follicle
- Luteum= lipid i.e. cholesterol for steroid production


When does the CL reach a mature state?

7-8 days following ovulation


What happens to steroidal production during the luteal phase?

Production of BOTH estradiol and progesterone
- LH binds theca-lutein cells & stimulates andostenedione formation
- Androstenedione is again converted to estradiol in the lutenized granulosa cells
- Additionally, there is an upregulation of the genes necessary to make progesterone in the lutenized-granulosa cells

Thus, BOTH the theca & granulosa cells respond to LH


What changes are seen in granulosa cells that helps them form progesterone?

- Upregulation of LDL receptors for cholesterol
- Enzymes necessary to form progesterone from cholesterol
- LH receptors on granulosa cells


What happens to the endometrial lining during the Luteal Phase?

Differentiation and secretory development that is regulated by PROGESTERONE

*This is the SECRETORY phase that gets ready for implantation


What are the key endometrial changes that occur during the luteal phase?

- Increased complexity of vascular and glandular structures
- Accumulation of substances in glands
- Deposition of lipids and glycogen in stromal cells
- Increased blood supply


Describe the feedback mechanisms of the Luteal Phase.

- Progesterone & inhibin A exert a negative feedback at the level of the ANTERIOR PITUITARY

*****Gonadotropin production declines & results in a decline in steroid production


When does the CL begin to regress? What does it become?

- 26th day
- Corpus albicans


What does the decline in estrogen & progesterone production of the Luteal Phase result in?

- Release of proteolytic enzymes that cause tissue lysis
- Increase in prostaglandin production that increases myometrial contraction

Note that progesterone normally INHIBITS these actions i.e. prostaglandins


What causes the menstrual cycle to restart again?

Low steroid levels relieve the negative inhibition on the HPG axis & gonadotropin production begins to rise again


If fertilization occurs, what allows invasion into the endometrium?

The blastocyst expresses multiple enzymes that allow invasion


How is steroid production maintained if there is fertilization?

If IMPLANTATION occurs, CL does NOT regress
- hCG stimulates ovarian steroidogenesis


What receptors does hCG bind to?

LH receptors; thus, hCG mimincs LH to maintain steroidogenesis & CL is maintained


When is there a transition in the dependence of the CL for steroids and the placenta?

8 weeks


Draw the relative concentrations of the gonadotropins during the menstrual cycle.



Draw the relative concentrations of the steroid hormones during the menstrual cycle.



What are the age related changes in hormone release that occur in puberty?

1) Low amplitude nocturnal pulses of gonadotropin release
2) Increased steroid production in response, which causes a number of physiological changes


What is menarche indicative of hormonally?

Estrogen-mediated endometrial growth


What age related hormonal changes occur in menopasue?

1) ~36 y/o loss of ovarian follicular activity
2) Decline in estradiol & inhibin
3) Results in a loss of negative feedback and upregulation of LH & FSH

*****There is a marked overall decline in estrogen production that leads to the negative effects of menopause

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