What causes menstrual flow?

Answer 1

I don't know how old you are, or if you are a boy or a girl; but I'll keep my answer simple.

Imagine you keep hoping a friend will come and stay with you, so you prepare a guest room complete with fresh flowers and a basket of fruit. When your friend doesn't come, you need to throw out the wilted flowers and the unwanted fruit.

In a similar way, a woman's body prepares itself for her "guest" by padding the walls of her womb (her uterus --- kind of like a little room in her body) and preparing a way to feed the baby guest. When no baby comes, the body "throws away" the padding (uterine lining) and the other stuff it was saving to make it nice and comfy for the little guest. Because it's coming out of a woman's body, it looks like blood...because that's what it mostly IS! Our blood carries oxygen and food around to all the cells in our body and carries away the trash our cells need to get rid of. The baby guest, too, would need oxygen, food, and something to carry away its waste. but, sadly (or luckily...depending!) no baby comes, so all that unneeded stuff is passed out of the woman's body near the same area that other waste comes out, and it starts all over again the next month. This happens each month from about the time the girl is a young teenager until she is about 50!

I hope this helps.

if you're older, this answer may be more appropriate:

The menstrual cycle is a recurring cycle of physiologic changes that occurs in reproductive-age females. Overt menstruation (where there is blood flow from the vagina) occurs primarily in humans and close evolutionary relatives such as chimpanzees.[1] Females of other species of placental mammal undergo estrous cycles, in which the endometrium is completely reabsorbed by the animal (covert menstruation) at the end of its reproductive cycle. This article focuses on the human menstrual cycle.

The menstrual cycle, under the control of the endocrine system is necessary for reproduction. It may be divided into three distinct phases: menstruation, the follicular phase and the luteal phase.[2] Ovulation defines the transition from the follicular phase to the luteal phase. The length of each phase varies from woman to woman and cycle to cycle, though the average menstrual cycle is 28 days.[2] Hormonal contraception interferes with the normal hormonal changes with the aim of preventing reproduction.

Stimulated by gradually increasing amounts of estrogen in the follicular phase, menses slow then stop, and the lining of the uterus thickens. Follicles in the ovary begin developing under the influence of a complex interplay of hormones, and after several days one or occasionally two become dominant (non-dominant follicles atrophy and die). Approximately mid-cycle, 24-36 hours after the Luteinizing Hormone (LH) surges, the dominant follicle releases an ovum, or egg in an event called ovulation. After ovulation, the egg only lives for 24 hours or less without fertilization while the remains of the dominant follicle in the ovary become a corpus luteum; this body has a primary function of producing large amounts of progesterone. Under the influence of progesterone, the endometrium (uterine lining) changes to prepare for potential implantation of an embryo to establish a pregnancy. If implantation does not occur within approximately two weeks, the corpus luteum will involute, causing sharp drops in levels of both progesterone and estrogen. These hormone drops cause the uterus to shed its lining in a process termed menstruation.

In the menstrual cycle, changes occur in the female reproductive system as well as other systems (which lead to breast tenderness or mood changes, for example). A woman's first menstruation is termed menarche, and occurs typically around age 12. The end of a woman's reproductive phase is called the menopause, which commonly occurs somewhere between the ages of 45 and 55.

*hope this answers your question! *

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Answer 2

Menstruation, (Or more commonly known as periods) happens to every girl or woman of a certain age. It is where the protective womb lining (That protects a baby if you fertilise an egg) exits the body as the girl's egg has not been fertilised. It happens because your egg has not been fertilised by a sperm, and your body tells you that you do not need your womb lining, as there is no more baby!

Answer 3

Its the hemorraging of a follicle in the uterus due to not being fertilized. There are, plus or minus, about 450 egg sacs in the uterus that have potential for fertilization. When this does not occur the body gets rid of the unused material resulting in menstruation. When the eggs run out, a woman goes through menopause. Hope that's the answer you were looking for!