36.2.3 - Oogenesis / Ovarian cycle

Question 1

Function - Stimulating the follicle – Growth during the follicle phase

Produces / Releases - Anterior Pituitary

Stimulates Release - Negative Feed Back Loop -

Low Levels Estradiol

Peak - 0-13 Days

Answer 1

FSH - Follicle-stimulating Hormone

Question 2

Function - Trigger Ovulation (release of mature egg from ovary) formation of corpus luteum

Produces / Releases - Anterior Pituitary

Stimulates Release - Negative Feed Back Loop -

Low Levels Estradiol

Peak - 0-13 Days

Answer 2

LH - Luteinizing hormone

Question 3

Function - Follicle growth, Female Sex characteristics, Buildup of uterine lining

Produces / Releases - Cells in Follicle

Stimulates Release - Negative Feed Back Loop - Low Levels Estradiol (Buildup of uterine lining)

Positive feedback from rising estrogen levels (surge in GnRH and releases of LH)

Peak - Day Around day 13 (Just before ovulation occurs)

Answer 3

Estrogen / Estradiol

Question 4

Function - Prepares uterine lining from fertilized egg and maintains corpus luteum

Produces / Releases - Corpus Luteum after ovulation

Stimulates Release - Rising LH levels during luteal phase

Peak - Luteal phase after ovulation

Answer 4

Progesterone

Question 5

3 Phases of the Ovarian Cycle
(Slide 4)

Answer 5

Follicular
Ovulation
Luteal

Question 6

Follicular

Answer 6

Negative Feedback suppressing LH and FSH (0-13 Days)

-Follicles in the Ovary begin to develop

-As they grow, more estrogen (estradiol) is released

-Sets Stage for ovulation

Question 7

Luteal

Answer 7

Second half of menstrual cycle (15-20)

-Corpus Luteum forms (after ovulation) and secrete progesterone

-If fertilized corpus luteum is maintained / otherwise, it degrades (no fertilization)

The luteal phase supports early pregnancy (preparation for the next cycle)

Question 8

Ovulation

Answer 8

Release of the oocyte into the fallopian tube (Around 13)

-Triggered by high Levels of LH

-Allows egg to become fertilized

Question 9

High estrogen–positive feedback stimulates FSH and LH (luteal phase)

The hypothalamus is stimulated by high levels of estradiol (estrogen)

Precisely time ovulation allowing the egg to be fertilized (Increase the amount of LH / Surge to trigger ovulation)

ALLOWS HORMONE LEVELS TO FLUCATE

Answer 9

Feed Back Loop Positive

(Slide 5 / 7)

Question 10

Progesterone - Estrogens = Negative Feedback

Low Estrogen – negative feedback suppressing LH and FSH (follicular phase)

The hypothalamus and Pituitary are inhibited by low levels of estradiol/progesterone.

Prevent overstimulation of ovaries

Answer 10

Feedback Loop Negative

(Slide 6 / 7)

Question 11

If no pregnancy

Answer 11

The Corpus Luteum degenerates in 2nd half of the luteal phase.

Estrogen & Progesterone levels go down = shedding of uterine lining (menstrual period)

Question 12

If pregnancy

Answer 12

Implants in the uterine lining

Embryo secrets HCF (human chorionic gonadotrophin

HCG stimulates the growth of the corpus luteum

Estrogen and Progesterone levels rise = growth of uterine lining and other pregnancy-related changes