Menstrual Cycle

MENSTRUAL CYCLE

Maria Nazarethe A. Sulit, RN

What is menstruation? Menstruation is the periodic shedding of the endometrium accompanied by blood loss, that identifies the reproductive years of a woman's life.

Menstrual Cycle Prepare for pregnancy Ave. 28 day cycle As short as 20 days As long as 45 days

Hypothalamic-Pituitary Cycle

Ovarian Cycle • Follicular phase (Day 1-14)  Time before ovulation  LH surge causes ovulation  Ovarian follicle mature under the influence of FSH & estrogen  1st day of menstruation until ovulation  Very variable period  24-46 hrs before ovulation Estrogen & LH

Ovarian Cycle • Luteal phase (Day 15-28)  Period following ovulation  Ovum discharged from mature follicle  Corpus luteum develops under the influence of LH  Corpus luteum life span is 7 days  Degeneration of CL=decrease in progesterone  Fertilization: zygote secretes HCG  Fixed 14 days after ovulation=menstruation

Ovarian Cycle

Layers of the Endometrium

Endometrial Cycle • Menstrual Phase  1st day of menstruation to 5 days  Menstruation: regression of the corpus luteum & decline in estrogen & progesterone  2/3 of endometrium is shed off  Uterus lining is thinnest at this point  Blood loss 30-80 ml  Woman’s life span 10-20 liters blood loss

Endometrial Cycle • Menstrual Phase  Saturating more than 1 pad or tampon/hr or 8 pads/day = heavy flow  Average Iron loss 1229 mg  Fe supplements

Endometrial Cycle • Proliferative Phase  Follicular/Estrogenic phase  6 to 13 day  Endometrial surface is restored to normal thickness 4-5 days after the 1st day of menstruation  Estrogen promotes the growth of new cells & capillaries in the endometrium

Endometrial Cycle • Secretory Phase  14 to 25 day  Mittleschmerz  Spinnbarkheit

Endometrial Cycle • Secretory Phase  Progesterone causes dilation of blood vessels in the endometrium:spiral/corkscrew shape  Increase vascularity of the uterus  Endometrial glands elongate, more active & secrete glycogen containing fluid  Endometrium becomes soft, spongy, edematous, very rich in nutrients & blood

Endometrial Cycle • Ischemic Phase  Regression of corpus luteum  Decrease in progesterone  Formation & release of protaglandin & endothelin 1  Vasospasm of spiral arteries & contraction myometrium  Vasospasm ischemia necrosis rupture of blood vessels sloughing off