Menstrual Cycle: Anatomy & Physiology

menstrual cycle: define

-a series of events that occur over a period of 28 days that relate to the growth and degeneration of the female endometrium

Secretory Phase: No implantation

-decrease secretions of estrogen and progesterone from degenerating corpus luteum initiate another menstruation to occur --> cycle starts over again

Menopause

-last menses or menstrual cycle -onset: 45-55 -due to decreased production of estrogen by the ovaries

Menarche

-the first menses or menstrual cycle -onset: 11-13 years old -must have enough body fat for estrogen production

Days 6-13

Proliferative Phase -estrogen from developing follicles stimulates repair and thickening of endometrium -this readies the ovum for implantation if fertilized

Days 1-5

Menstrual Phase -degeneration and shedding of the superficial portion of the endometrium -comprised of blood, tissue fluid, mucous, and epithelial cells.

Days 15-28

Secretory Phase -progesterone production from corpus luteum continues thickening of endometrium -increased vascularity from elongated vessels -endometrial glands enlarge, producing mucus-rich glycogen --> nutrition for implanted egg