Female sexual cycle with menstruation.pptx

about menstruations

1. Female sexual cycle

2. One follicle, possibly the one with the best blood supply, secretes more estradiol than the others. Because estradiol acts locally within the follicle to increase the granulosa cell’s sensitivity to FSH, this follicle becomes the dominant follicle, i.e., the one destined to grow and rupture. The remaining follicles, lacking sufficient FSH, synthesize only androgen and become atretic (die).

3. Estrogen: Some of the estrogen produced by the granulosa cells is released into the blood and inhibits the release of LH and FSH from the anterior pituitary. However, another fraction of the estrogen acts locally on granulosa cells, increasing their proliferation and sensitivity to FSH.

4. Granulosa cells also release inhibin B. Inhibin B inhibits the secretion of FSH.

5. Peripheral effects of estrogen produced by granulosa cells during follicular phase Rising levels of estrogens cause the endometrial cells of the uterine mucosal layers to increase their rate of mitotic division (proliferate). Circulating estrogens cause the cervical mucus to be thin and watery, making the cervix easy for sperm to traverse . under the influence of estrogen, vaginal epithelial cells become cornified (keratinized)

6. Ovulation is always 14 days before the end of the cycle. Notice from the figure that the LH surge and ovulation occur after estrogen peaks. Therefore, if estrogens are still rising, ovulation has not occurred.

7. Follicular rupture occurs 24–36 hours after the onset of the LH surge. During this time interval, LH removes the restraint upon meiosis , which has been arrested in prophase for years. The first meiotic division is completed, and the first polar body is extruded

8. Preovulatory Follicle In the latter stages of the follicular phase, intracellular changes within the granulosa and theca cells occur in preparation for their conversion into luteal cells. Estradiol , in conjunction with FSH, causes the granulosa cells to produce LH receptors. The metabolic pathways are then altered to favor the production of progesterone. This would include a decrease in the activity of aromatase and a drop in estrogen production.

9. Luteal phase… The glandular cells store glycogen and secrete large quantity of carbohydrate-rich mucous and fluid . Therefore, this phase is called secretory phase Under the influence of progesterone, vaginal epithelium proliferates and secretes a thick mucous . The epithelium is infiltrated with leucocytes and cornification decreases

10. The pattern of change in concentration of inhibin B coincides with the change in concentration of FSH , whereas the concentration of inhibin A coincides with the pattern of progesterone

11. The process of luteinization occurs following the exit of the oocyte from the follicle. The life of the corpus luteum is finite, hence the luteal phase is only 14 days. Progesterone exerts negative feedback on LH, which contributes to the demise of the corpus luteum . With the demise of the corpus luteum , progesterone and estradiol fall to levels that are unable to support the endometrial changes, and menses begins .

12. Menstruation is caused by the reduction of estrogens and progesterone, especially progesterone, at the end of the monthly ovarian cycle.

13. Estrone : This is the main circulating estrogen following menopause.

14. bleeding phase is part of the follicular phase and ovulation is not a separate phase Follicular phase of ovarian cycle = menstrual and proliferative phase of endometrial cycle Luteal phase of ovarian cycle = secretory phase of endometrial cycle

15. Determination of day of ovulation helps in family planning .