This is normal and natural. http://en.wikipedia.org/wiki/Menstruation
The lining of the blood passing out of the vagina is known as a woman's monthly period. It is natures way to strip the old lining of the Uterus that failed to be needed on the woman becomes pregnant. The lining is rebuilt (renewed) to prepare for a possibly future pregnancy.
the lining of the uterus thickens,
The uterus lining will come loose and a mentral cycle will begin.
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Every month, the uterus prepares for the possibility of pregnancy, so if nothing happens, the uterus sheds the lining and passes out of the body.
Menstruation results in the discharge of the uterus lining, consisting of blood and tissue.
Menstruation
menstruation
Menstruation is the process in which the uterus lining breaks down and leaves the body - thus menstrual flow consists of uterus lining and blood from the uterus lining breaking down, it can also contain cervical mucus picked-up while the menstrual flow passes through the vaginal opening, and discharge from within the vagina.
hormone that maintains the lining of the uterus?
A women without a uterus cannot menstruate, by definition: (of a woman) discharge blood and other material from the lining of the uterus as part of the menstrual cycle.
The lining of the uterus breaking apart is the mucus lining that is usually formed so as to create a conducive environment for a fertilized egg to develop. If the ovum is not fertilized, the thick lining breaks apart which is what causes menstruation.
The soft lining of the uterus sheds monthly. I suppose you could "scratch" it, but it would be the equivalent of the wind blowing at the tear film of your eye.
The lining of the uterus is what denigrates when your egg isn't fertilized and you get your period.
The lining of the uterus serves as a protection for the growing fetus.
A period is when a woman's uterus lining breaks down and exits her body through her vagina. This happens on a monthly basis.
Cramps are caused by the uterus to expel its lining.