Where does my period come from?

If you want to understand the origin of menstruation, you must first understand the normal physiological structure of women. When women reach puberty and their uterus gradually matures, they begin to ovulate and menstruate, and blood will be secreted. A large amount of blood will flow or be directly discharged, and it will last for several days. After these periods, the blood in the uterus disappears and the vagina will no longer secrete.

To explain this issue, we must first understand the structure of women's reproductive organs and their physiological functions. The female internal reproductive organs consist of the ovaries, uterus, and fallopian tubes. The main function of the ovaries is to produce eggs and synthesize ovarian hormones, while the uterus and fallopian tubes are reproductive organs. The ovaries contain hundreds of thousands of follicles, each of which contains one egg.

Before puberty, the follicles are essentially non-functional. During puberty, under the action of gonadotropin from the anterior pituitary gland, immature follicles gradually develop and synthesize estrogen. When the follicle matures and ovulates, the follicle wall collapses, the cells become larger and yellower, and are called the corpus luteum. It synthesizes estrogen and produces progesterone.

As the ovaries change, the endometrium is also affected and undergoes corresponding cyclical changes. Estrogen causes the endometrium to thicken, the endometrial cells to increase in number and size, and the arterioles in the interstitium to become more tortuous and spiral, which is called the proliferative endometrium. After ovulation, due to the combined effects of estrogen and progesterone, the endometrium becomes edematous, the glands produce a large amount of mucus and glycogen, and the thickness of the endometrium increases from 1 mm to 6 mm, which is called the secretory endometrium.

If the egg released at this time is fertilized, the fertilized egg is transported to the uterus through the fallopian tube for development, which is called pregnancy. The pregnancy tissue synthesizes a chorionic gonadotropin, which supports the continued development of the corpus luteum of the ovary. If the egg is not fertilized, the corpus luteum will atrophy and stop secreting estrogen and progesterone about 14 days after ovulation. At this time, the blood vessels in the endometrium will contract, the endometrium will necrotize and fall off, causing bleeding and forming menstruation.

Therefore, the length of the menstrual cycle depends on the length of the ovarian cycle, which is generally 21-30 days, but varies from person to person, and may be 23-45 days, or even 3 months or half a year as a cycle. As long as it is regular, it is generally considered normal menstruation.

The bleeding time is generally 3-7 days, and the total amount of bleeding each time is 30-50ml. Some people believe that menstrual volume exceeding 80ml is a pathological condition.