Exam #4: Female Reproductive Physiology II

Question 1

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

Answer 1

• 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

Question 2

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

Answer 2

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

Question 3

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

Answer 3

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

Question 4

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

Answer 4

Theca externa= capsule of the follicle

Theca interna= hormone producing

Question 5

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

Answer 5

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

Question 6

What causes the atresia of the non-dominant follicles?

Answer 6

Decline in FSH that may be induced by Inhibin B

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

Question 7

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

Answer 7

Prolifeation of the uterine endometrium

• stromal cells
• growth of endometrial glands
• blood vessel development
• mucus secretion

*Note that this is regulated by estrogen

Question 8

When does estrogen peak?

Answer 8

Just before day 14 i.e. just before ovulation

Question 9

What is the effect of the estrogen peak?

Answer 9

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

Question 10

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

Answer 10

• Day 14

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

Question 11

What is absolutely required for ovulation?

Answer 11

LH surge at Day 14

NO LH = NO ovulation

Question 12

What happens to progesterone levels after ovulation?

Answer 12

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

Question 13

What effect does progesterone have on basal body temperature?

Answer 13

Increase in basal body temp

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

Question 14

What are basal body temperature measurements used for?

Answer 14

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

Question 15

What is the corpus luteum?

Answer 15

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

Question 16

When does the CL reach a mature state?

Answer 16

7-8 days following ovulation

Question 17

What happens to steroidal production during the luteal phase?

Answer 17

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

Question 18

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

Answer 18

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

Question 19

What happens to the endometrial lining during the Luteal Phase?

Answer 19

Differentiation and secretory development that is regulated by PROGESTERONE

*This is the SECRETORY phase that gets ready for implantation

Question 20

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

Answer 20

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

Question 21

Describe the feedback mechanisms of the Luteal Phase.

Answer 21

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

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

Question 22

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

Answer 22

• 26th day

- Corpus albicans

Question 23

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

Answer 23

• 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

Question 24

What causes the menstrual cycle to restart again?

Answer 24

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

Question 25

If fertilization occurs, what allows invasion into the endometrium?

Answer 25

The blastocyst expresses multiple enzymes that allow invasion

Question 26

How is steroid production maintained if there is fertilization?

Answer 26

If IMPLANTATION occurs, CL does NOT regress

- hCG stimulates ovarian steroidogenesis

Question 27

What receptors does hCG bind to?

Answer 27

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

Question 28

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

Answer 28

8 weeks

Question 29

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

Answer 29

N/A

Question 30

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

Answer 30

N/A

Question 31

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

Answer 31

1) Low amplitude nocturnal pulses of gonadotropin release

2) Increased steroid production in response, which causes a number of physiological changes

Question 32

What is menarche indicative of hormonally?

Answer 32

Estrogen-mediated endometrial growth

Question 33

What age related hormonal changes occur in menopasue?

Answer 33

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