Period cycle is a physiological cycle that occurs in some of the fertile females like humans and chimpanzees and other hominids between. Cows, mares, female camel, sow, ewe, etc. have periods too, some of the mammalian mammals are experiencing the estrous cycle.
Women of childbearing age and primates female animal normally every month or so, endometrial cells occurs independent thickening, vascular proliferation, glandular secretion and growth, endometrial crash off accompanied by bleeding cycle changes.
This periodic vaginal discharge of blood or bleeding phenomenon called period or menstruation.
The main constituents of menstrual blood or period blood (3/4 arterial blood, 1/4 veins blood), endometrial tissue fragments and a variety of active enzymes and biological factors.
Wherein the fibrinolysis enzyme make menstrual blood stay liquid, without coagulation, prostaglandins make the uterus contraction.
I medical only the reproductive cycle of primates (including humans) is called menstruation or period, beside primates, other mammals reproductive cycle are called the estrous cycle, periods regulation by the reproductive hormone system, is biological reproduction needs.
A woman's first menstruation or period is called menarche, and menarche marks the women has entered puberty.
Women menarche at an average age of 12. Genetic, diet and physical health and so many other factors can advance or delay the arrival of menarche.
Stop menstruation marks women have entered the menopause, also known as menopause.
Menopausal women average age 51 years old, of course, just as menarche as genetic, illness, surgery and medical treatment, and so many factors can make menopause comes earlier or later, 40-58 years old entered the menopause stage are a normal phenomenon. And menopause before the age of 35 arrival is defined as premature.
To explain, first need understand the female reproductive organs structure and physiological functions.
Internal genital organs of female including ovaries, uterus, fallopian tubes.
The main function of the ovaries is to produce eggs and synthetic ovarian hormones, the uterus and the fallopian tubes are reproductive organs, ovaries contain hundreds of thousands of follicles, each follicle containing an egg.
Before puberty follicular basically has no function. During adolescence, cause of the pituitary anterior lobe gonadotropin, immature follicles gradually developed, at the same time synthetic estrogen.
When follicular maturation and ovulation, the follicle wall collapse, the cell becomes large, yellow, called corpus luteum, which synthetic estrogen, produces progesterone at the same time. When follicular maturation and ovulation, the follicle wall collapse, cell becomes large, yellow, called corpus luteum, which synthetic estrogen, produces progesterone at the same time.
With the changes in ovarian, the endometrial cell is affected, corresponding changes will occur.
Estrogenic hormone make endometrial cyst thick, endometrial cells quantity increase, small interstitial arteries become a more tortuous spiral, called proliferative uterine endometrium.
After ovulation, due to the combined effect of estrogen and progesterone, endometrial cell edema, glands produce large amounts of mucus and glycogen, endometrial thickness increased from 1 mm to 6 mm, called secretory uterine endometrium.
If at this time the discharged egg fertilized, and the fertilized egg gets into the uterus through the fallopian tubes to develop, known as pregnancy, pregnancy tissue synthesis a human chorionic gonadotropin, which supports ovarian corpus luteum continue to develop.
If the egg does not fertilize at ovulation after about 14 days, corpus luteum shrivel, secretion of estrogen and progestin stop, the blood vessels in the endometrium cell contract, endometrial necrosis and fall off, causing bleeding, period, menstrual period happen.
Therefore, the menstrual cycle length, depending on the ovarian cycle length, usually 28-30 days, but varies base on different women, there are 23-45 days, or even three or six months as a period.
As long as there is regular cycle length, usually it is the normal menstruation.
Bleeding time is usually 2-7 days, every menstrual bleeding total of 30-50ml. Some people think that menstrual flow more than 80ml is a pathological state.