One of the chief sign that a girl is turning into a woman is menstruation or the episodic shedding of the endometrium in response to hormonal change. It is also a process in which the body prepares for implantation of the fertilized egg, by shedding the old endometrium, the body can again prepare for a possible conception.
Like a lot of changes regarding puberty, menstruation can be confusing. Not a lot of people know that the purpose menstruation is to renew the tissue bed of the uterus so that it will be able to entertain a fertilized egg, allowing it to grow once it is implanted. The first menstrual period in girls is termed as the menarche. How long the menstrual cycle takes place is variable, it differs from woman to woman but the accepted average duration is 28 days and the accepted average duration for the flow of blood or menstrual flow is around 4 – 6 days.
The Physiology of MenstruationCredit: http://nursingcrib.com/news-blog/physiology-of-menstruation/
It is important to remember the four key structures that is responsible for the menstrual cycle and these structures are the ovaries, hypothalamus, pituitary gland and the uterus. Failure of any of these four structures will lead to an ineffective or incomplete cycle.
In performing its part in the menstrual cycle, the hypothalamus releases GnRH or gonadotropin releasing hormones thereby signalling the start of the menstrual process. However, this mechanism can be countered by oestrogen since if there is an increased level of oestrogen, there will be a repression in the production of GnRH. As girls age, the hypothalamus becomes less sensitive to oestrogen which allows for the menstrual cycle to occur monthly.Credit: http://www.peruviannaturistasmedicines.com/menstrual_colics_salpingitis_irregularity_delays_menstruations_vaginal_hemorrhages_ovarian_cysts.php
GnRH, coming from the hypothalamus is then transported to the pituitary gland, to be more precise, the anterior pituitary gland which then becomes excited and released FSH or follicle stimulating hormone and LH or luteinizing hormone. Even though the anterior pituitary gland produces these two hormones, they act on varying stage of the menstrual process. The FSH acts early in the cycle hence causing the ovum to mature. When the egg cell is mature, it is released from the ovary and these are made possible by the LH. The Luteinizing hormone is active in the second half of the cycle which causes the lining of the uterus to thicken.
After a surge of LH, the follicles then rupture and are discharge from the ovaries. At this moment, the FSH levels subside while the LH continues to rise in amount. Progesterone is the hormone responsible for the slight increase in temperature a woman experiences, although it may not be noticeable, since progesterone is thermogenic. If the egg cell is not fertilized, it degenerates after 4 – 5 days and is expelled from the body.
The endometrium layer then sheds and we refer to this as the “menstruation” which allows the body to again prepare for possible conception and implantation.Credit: http://classprojects.kenyon.edu/wmns/Wmns36/bloodflow/medical.htm
Although women may say that they are shedding large quantities of blood during menstruation, in reality they are only shedding around 30 to 80 ml of blood. Let us not forget that the menstrual flow is not composed solely of blood but also with the other components of the menstrual cycle like mucus and endometrial shreds. The amount of iron loss during menstruation is significant that women may need to take iron supplement to prevent iron depletion.
It is good to inform not only the girls who will be undergoing the menstrual cycle but also the parents so they will understand that this process is not just the shedding of the endometrial layer but a preparation of the body for conception and implantation. Menstruation signals that the body is ready for the important internal function it represents.