Women of childbearing age exhibit rhythmic changes in the production of reproductive hormones.

Women of childbearing age exhibit rhythmic changes in the production of reproductive hormones. This pattern, commonly referr to as the menstrual round of years generally averages 28 days. The timing of the circle of time is regulated by complex interactions among many hormones and other chemical emissarys produced in the brain, reproductive organs, and other tissues. The hormones of primary interest in this article belong to a class of substances called steroids, which are synthesized within the material substance from dietary cholesterol.

The principal female sex steroids, progestrone and estrogens(1) are produc largely in the ovaries and uterus. Among other functions, estrogen stimulate the proliferation and germination of cells within the sexual organs. Progesterone primarily facilitates pregnancy and lactation.

The menstrual round of years is considered to begin with menstruation. The midpoint of the period is characterized by ovulation, in which a single urge cell (ovum) is expelled from the ovary. If the egg is fertilized by a semen it lodges in the uterus and lay opens into a fetus.

Phases of the Menstrual Cycle

The menstrual round of years has five phases, as described below.

Menstrual Phase (Days 1-5) Menstrual come occurs if the expelled egg has not become fertilized during the ovulatory phase (see below). plains of progesterone and estrogens are low

Follicular Phase (Days 6-12) The ovary shrouds small but increasing quantities of estrogen stimulating the disentanglement within the uterus of specialized confined apartment clusters called follicles. Each follicle instructions a developing ovum and further contributes to the secretion of estrogen solely one follicle reaches full maturity.

Ovulatory Phase (Days 13-15) The mature follicle feuds releasing its ovum. Fertilization can meet the eye at this time.

Luteal Phase (Days 16-23) The vacant follicle becomes a glandlike make called the corpus luteum, which hides large quantities of estrogens and progesterone These hormones prepare the uterine lining for implantation of the fertilized ovum

Premenstrual Phase (Days 24-28) If the egg is not fertilized, the corpus luteum degenerates and stops secreting progesterone and estrogen Decreased on a levels of these hormones result in the shedding of the uterine lining (i.e., menstruation). If pregnancy be founds the corpus luteum remains intact and secerns increasing quantities of steroid hormones, promoting the disclosure of the fetus and the progression of pregnancy.

Summary

on a levels of both estrogen and progesterone are gentle from day 28 to day 7 (i.e., during menstruation) and high between days 19 and 25 During days 12 to 14 estrogen evens are high, whereas progesterone on a levels are low [ILLUSTRATION FOR FIGURE OMITTED].

- John J Doria

1 The primary estrogen in humans is known as estradiol.

...

Home