Female Reproductive Cycle Flashcards
What is important in the ovary cycle?
Estradiol
Progesterone
What is important in the uterine cycle?
FSH
LH
What are the two phases of the ovarian cycle?
Follicular (before menstruation)
Luteal (after menstruation)
What are the three phases of the uterine cycle?
Menstruation
Proliferation
Secretory
What occurs in the proliferative phase?
The endometrium proliferates and begins to form secretory cells
What occurs in the secretory phase?
The secretory cells are ready to secrete what is needed in case the egg is implanted
Why are P4 and E2 declining at the end of a cycle?
Because they are inhibiting GnRH so FSH and LH are not being secreted in order to stimulate their release (corpus luteum is not being maintained)
What cells produce E2?
Granulosa cells
What cells produce P4?
Theca interna cells
What occurs if an embryo implants into the endometrium?
The endometrium will begin to secrete hCG
What does hCG do?
It has FSH and LH activity so it can continue to stimulate the corpus luteum to continue to create P4 and E2
What does FSH stimulate pre-ovulatory?
Granuloma cells
What does LH stimulate pre-ovulatory?
Theca interna cells
What occurs in the 1st stage of the pre-ovulatory cycle?
FSH and LH increase binding to granulosa and theca interna cells causing and increase in E2 production (no P4 increase yet)
What occurs in the 2nd stage of the pre-ovulatory cycle?
Estradiol is increasing which causes a decrease in GnRH and therefore LH and FSH due to negative feedback
What occurs in the 3rd stage of the pre-ovulatory cycle?
The dominant follicle notices a decrease in FSH and LH so it upregulates its FSH and LH receptors stealing what is left of the two from the other follicles causing them to die off and it begins to produce large amounts of E2, once E2 reach a threshold of 600 pg/mL it switches from a negative to a positive feedback on GnRH causing a surge in FSH and LH
What occurs in the 4th stage of the pre-ovulatory cycle?
LH stimulates theca interna cells to start producing more P4 causing and increase in proteins necessary to weaken the follicular wall and inhibit OMI
What is OMI?
Ovum maturation inhibiting hormone
What stage does OMI keep the ovum in?
Prophase I
What occurs to theca interna and granulosa cells once ovulation occurs?
They collapse and stop making estradiol and stop the positive feedback on the hypothalamus to release GnRH; as the cells recover they become the corpus luteum and then begin to produce E2 and P4 again
What does inhibin inhibit?
FSH only
When does inhibin peak?
Prior to ovulation
What occurs if inhibin is not reduced by the end of the cycle just prior to menstruation?
You will not have release of FSH and a new follicle cannot be stimulated
What is the pulse generator of GnRH?
A decapeptide is released from cells surrounding the Arcuate nucleus in the hypothalamus that releases GnRH in a pulsatile manner
How many times per day is GnRH released in a pulsatile way?
Every 90 minutes so 16 times per day
What receptors are found on granulosa cells during luteal phase?
LH and FSH receptors
Now have the enzyme needed for P4 production
What receptors are found on the theca interna cells during the luteal phase?
LH receptors
Why do granulosa cells have LH receptors during the luteal phase?
So that they can produce also produce P4 to help the theca interna cells in keeping the uterus in the secretory phase
Primary steroid hormone in follicular and luteal phase?
Follicular: Estradiol
Luteal: Progesterone
What is endometriosis?
Endometrial cells make it into the peritoneum and implant and begin to grow with each menstrual cycle
How do you treat endometriosis?
Constant GnRH to stop the menstrual cycle
What does constant GnRH cause?
Inhibition of FSH and LH release since the anterior pituitary does not respond to continuous GnRH
How do you treat infertility in a healthy female that simply isn’t menstruation?
GnRH pulsatile every 90-120 minutes
What causes movement of the cilia in the fallopian tube to move the egg?
An increase in estradiol
What does Activin do?
Stimulates FSH
What secretes inhibin?
Thecal cells
