menstrual and its most disfunctions.pptx

Menstrual disfunctions

1. Female hormonal system Reproductive function in the female is regulated by interactions of hormones from the hypothalamus, anterior pituitary, and ovaries. • Gonadotropin-releasing hormone (GnRH) is the releasing factor from the hypothalamus that stimulates secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. The release of GnRH is inhibited by estrogen and progesterone. • LH is secreted from basophilic cells of the anterior pituitary gland and stimulates development of the corpus luteum in the ovaries. • FSH is secreted from the basophilic cells of the anterior pituitary gland in response to GnRH and stimulates development of the follicles in the ovaries. • Estrogen and progesterone are the steroid hormones secreted by the follicle and corpus luteum of the ovary. The 28-day period of the female sexual cycle is determined by the time required for the development of the follicles and corpus luteum after menstruation and the feedback effect on the hypothalamus of the hormones they secrete.

2. The menstrual cycle encompasses the ovarian and uterine cycles. The ovarian cycle describes changes that occur in the follicles of the ovary. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. Uterine cycle describes changes in the endometrial lining of the uterus. The uterine cycle prepare and maintain the lining of the uterus.

3. Monthly ovarian cycle One mature ovum is released from the ovary during each monthly cycle, and the endometrium of the uterus is prepared for implantation of the fertilized ovum at the appropriate time. To achieve these results, all of the hormones of the female reproductive system must interact. Menstrual cycle A normal menstrual cycle lasts 24-38 days( 28 days on average). Menses lasts an average of 3-7 days,with an average blood loss of 35-50ml.

4. Key Events in the Menstrual Cycle There are four key events that comprise a typical menstrual cycle: follicular phase, ovulation, luteal phase and menstruation Follicular phase can fluctuate in length Luteal phase is a fixed 14days,after which menstruation occurs. Estrogen stimulates endometrial proliferation. Progesterone maintains endometrium to support implantation. Low progesterone levels - decresed fertility.

5. Follicular phase and ovulation Follicle stimulating hormone (FSH) is secreted from the anterior pituitary and stimulates growth of ovarian follicules . The dominant follicule produces estrogen, which inhibits FSH secretion (negative feedback) to prevent other follicules growing. Estrogen acts on the uterus to stimulate the thickening of the endometrial layer. Midway through the cycle (~ day 12), estrogen stimulates the anterior pituitary to secrete hormones (positive feedback). This positive feedback results in a large surge of luteinizing hormone (LH) and a lesser surge of FSH. LH causes the dominant follicule to rupture and release an egg – this is called ovulation. Ruptured follicular cells differentiate into the corpus luteum.

6. Luteal phase and menstruation Change from estrogen to progesterone predominance: corpus luteum produces progesterone and some estradiol,allowing to act on the uterus to thicken the endometrial lining (in preparation for pregnancy). If fertilisation occurs, the developing embryo will implant in the endometrium and release hormones to sustain the corpus luteum. If fertilisation doesn’t occur, the corpus luteum eventually degenerates (forming a corpus albicans after ~ 2 weeks) When the corpus luteum degenerates, estrogen and progesteron levels drop and the endometrium can no longer be maintained The endometrial layer is sloughed away and eliminated from the body as menstrual blood (i.e. a woman’s period) As estrogen and progesterone levels are too low, there is no longer negative feedback to FSH, which then increases restarts cycle again.

7. Hormonal feedback loop The   hypothalamus  releases  gonadotropin -releasing  hormone  ( GnRH ) → stimulates  anterior pituitary  gland to release  follicle-stimulating   hormone   ( FSH ), luteiizing hormone(LH). FSH  recruits a group of  maturing follicles  in the  ovary  → growing follicles produce  estradiol  and   inhibin A  at increasing levels →  negative feedback  to the  pituitary gland  → inhibits the release of  FSH . One follicle becomes the  dominant follicle   and  estradiol  levels peak at the day before the  luteinizing hormone  ( LH ) surge →  high levels of  estradiol  induce  positive feedback  to the  pituitary gland  →   LH  levels increase. LH surge induces  ovulation  → the mature  oocyte  is released from the  dominant follicle  and the  corpus luteum   produces progesterone → increase in  progesterone  inhibits LH surge. Falling  LH  levels cause resolution of the  corpus luteum  → fall in progesterone and  estradiol  levels. The hormonal feedback loop is also influenced by other  hormones  (e.g.,  prolactin ).

8. Summary of Ovarian cycle About every 28 days, gonadotropic hormones from the anterior pituitary gland cause about 8 to 12 new follicles to begin to grow in the ovaries. One of these follicles finally becomes “mature” and ovulates on the 14th day of the cycle. During growth of the follicles, mainly estrogen is secreted. After ovulation, the secretory cells of the ovulating follicle develop into a corpus luteum that secretes large quantities of both major female hormones, progesterone and estrogen. After another 2 weeks, the corpus luteum degenerates, whereupon the ovarian hormones estrogen and progesterone decrease greatly, and menstruation begins. A new ovarian cycle then follows.

9. Premenstrual syndrome(PMS) The onset of severe discomfort or functional impairment prior to menstruation. Diagnostic criteria: Present in the 5 days prior to the beginning of menstruation for at least 3 consecutive cycles. End with 4 days after the beginning of menstruation. Interfere with normal daily life activities. Epidemiology: UP to 12% of female individuals.