Gracelyn Menstruation, also known as menstrual cycle, is a physiological cycle that occurs in some fertile women. female between humans and other hominins. Other mammals go through estrous cycles. Women of childbearing age and female primates, every one month or so, Uterus The endometrium undergoes cyclic changes such as autonomous thickening, blood vessel proliferation, glandular growth and secretion, and endometrial collapse and shedding accompanied by bleeding. This periodic vaginal discharge or uterine bleeding is called menstruation.
In adolescent women, due to the action of sex hormones secreted by the ovaries, the endometrium undergoes cyclic changes and is shed once a month. The shed mucosa and blood are excreted through the vagina. This bleeding phenomenon is menstruation. Because most people experience it once a month, it is called menstruation. The first menstrual period in a girl is called menarche, which is one of the important signs of puberty. The age of menarche is approximately 10 to 16 years old.
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. The uterus and fallopian tubes are reproductive organs. The ovaries contain hundreds of thousands of follicles, each of which contains one egg. Follicles are essentially nonfunctional before puberty. During puberty, under the action of gonadotropins from the anterior pituitary gland, immature follicles gradually develop and simultaneously synthesize estrogen. When the follicle matures and ovulates, the egg wall collapses and the cells become larger and yellower, called the corpus luteum, which not only synthesizes estrogen but also produces progesterone. As the ovaries change, the endometrium is affected by them and undergoes corresponding cyclic changes. Estrogen causes the endometrium to thicken, endometrial cells increase and enlarge, and the tubes become more tortuous and spiral-shaped, which is called the proliferative endometrium. After ovulation, due to the combined action 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 phase endometrium. If the egg discharged at this time is fertilized, the fertilized egg will be transported to the uterus through the fallopian tube to develop, 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 atrophies and stops secreting estrogen and progesterone about 14 days after ovulation. At this time, the blood vessels in the endometrium contract and the endometrium becomes necrotic and falls off, causing bleeding and menstruation. Therefore, the length of the menstrual cycle depends on the length of the ovarian cycle, which is generally 28-30 days, but varies from person to person, and can range from 23-45 days, or even 3 months or half a year. As long as it is regular, it is generally considered normal menstruation. The bleeding time is generally 2-7 days, and the total amount of bleeding during each menstrual period does not exceed 100 ml.
