Ovulation Cycle

Question 1

What are two functions of the ovaries?

Answer 1

1) Store oocytes

2) Produce hormones

Question 2

What are the four types of cells in the ovary?

Answer 2

1) Granulosa 2) Theca - make androgens which make estrogen 3) Stromal maintain estrone 4) Luteal make progesterone some estrogen and inhibin

Question 3

Where is GnRH releaesd from?

Answer 3

The hypothalamus

Question 4

Where is LH and FSH released from?

Answer 4

The pituitary gland

Question 5

What hormones communicate with the pituitary gland and the hypothalamus to give feedback?

Answer 5

Progesterone and Estrogen

Question 6

Slow GnRh release favours FSH or LH?

Answer 6

Slower GnRH release favours the secretion of FSH, which makes the ovaries develop follicles

Question 7

Fast GnRH release favours FSH or LH?

Answer 7

Fast GnRH release favours LH release which triggers the body to develop follicles and make the corpus luteum.

Question 8

What does inhibin do?

Answer 8

It slows down the secretion of FSH.

Question 9

What do high levels of estrogene do in terms of feedback?

Answer 9

Estrogen (without progesterone) stimulates high pulse frequency GnRH, LH and FSH release (positive feedback)

Question 10

There are 3 different types of estrogen, how are they different from one another?

Answer 10

1) Estrone (E1) - it’s weak. Made in ovaries and fat cells. Continues in menopause
2) Estrodiol (E2) - Most abundant in reproductive years. Made in ovaries, adrenal glands, liver, breast and fat cells. Decreases in menopause.
3) Estriol (E3) produced by the placenta during pregnancy.

Question 11

What is FSH’s main job?

Answer 11

Promotes growth of follicles. Granulosa (cells surrounding the oocyte) and theca cells (the cells surrounding the granulosa cells) have FSH receptors.

Question 12

What does LH work on and what does it do?

Answer 12

LH stimulates theca cells to make androgens which diffuse to granulosa cells that contain aromatase (activated by FSH).

Question 13

What happens in the early follicular phase?

Answer 13

FSH promotes the growth of follicles, LH stimulates theca cells to make androgens like aromatase and therefore estradiol

Question 14

What happens in the late follicular phase?

Answer 14

Granulosa cells release inhibin which inhibits FSH release. Estradiol levels increase. GnRH pulse frequency increases which favours LH release. LH stimulates theca cells to continue androgen synthesis and granulosa cells produce a bit of progesterone.

Question 15

How does the dominant follicle get chosen?

Answer 15

It is the one that makes the most estradiol and some progesterone compared to the other developing follicles

Question 16

What hormones are high during ovulation?

Answer 16

LH, GnRh, FSH, Estradiol, and progesterone kinda starts to get going .

Question 17

What happens during ovulation?

Answer 17

The first meiotic division is completed forming the secondary oocyte. The follicle fills with fluid. Progesterone, proteolytic enzymes and prostaglandings trigger follicle rupture and an oocyte gets released.

Question 18

How does body temperature relate to ovulation?

Answer 18

3 days of elevated body temperature means ovulation has occurred.

Question 19

How does clomiphene citrate (aka clomid or serophene) which are all fertility drugs work?

Answer 19

They block estrogen receptors in the hypothalamus (SERM) which inhibits the negative feedback of estrogen on GnRH release. This causes the pituitary gland to make more FSH and LH which increases recruitment of follicles and stimulates ovulation.

Question 20

What happens in the proliferative phase?

Answer 20

1) The endometrium grows - glands and arteries grow to feed the endometrium and make it viable for life
2) Progesterone receptors get upregulated and become more sensitive to progesterone.

Question 21

What do granulosa and theca cells become under the influence of LH to form the corpus luteum?

Answer 21

Luteal cells.

Question 22

What hormones are released from the corpus luteum?

Answer 22

Progesterone mainly, and estradiol, and inhibin.

Question 23

What happens to FSH and LH release after ovulation?

Answer 23

They decrease. GnRH pulse does frequent LH. Follicle growth is suppressed.

Question 24

Where is HCG released from?

Answer 24

In the event of fertilization, HCG gets released from cells of the blastocyst which prevents corpus luteum degeneration. The corpus luteum will produce it’s own hormones for 3 months until the placenta is fully functional.

Question 25

If fertilization doesn’t occur, what happens to the corpus luteum and the progesterone and estrdiol levels?

Answer 25

Corpus Luteum degenerates and estradiol and progesterone levels decrease. Then FSH will increase because of a low GnRH pulse frequency to recruit more follicles.

Question 26

How does progesterone play a roll in the secretory phase and work on the uterus?

Answer 26

Progesterone stimulates glandular secretion to secrete a thin glycogen rich fluid which feeds the potential egg.

Question 27

What are four roles of progesterone?

Answer 27

1) Thickens endometrium
2) Inhibits smooth muscle of myometrium which prevents contractions and allows the uterus to expand
3) Causes thickening of myometrium preparing it for the muscular work of labour
4) Promotes lobular breast tissue growth (but prevents lactation until baby is born)

Question 28

What happens to the corpus luteum at menses?

Answer 28

It becomes scar tissue

Question 29

What happens to endometrial arteries during menses?

Answer 29

They cut off blood flow to the functional layer. This causes endometrial cells to become ischemic, necrotic and they get sloughed off into the uterus.

Question 30

What causes contractions of myometrial smooth muscle?

Answer 30

A decrease in progesterone and an increase in inflammatory substances like prostaglandins.