In general, females start to menstruate between the ages of eleven and fourteen. The menstrual cycle goes through phases which are complicated and influenced by the human hormones generated and many diverse glands. The hypothalamus is a mind component that influences the adjoining pituitary gland to produce distinctive substances which arouse the ovaries to create the female and male sex hormones estrogen and progesterone. There are four key menstrual cycle phases: menstruation, follicular, ovulation and luteal.
Here is a breakdown of the different menstrual cycle phases:
Menstruation phase: Each month the thickened wall in your womb will excrete fluid through the vaginal canal. This is the menstruation fluid and it contains cells from your uterus wall, mucus and blood. Menstruation normally last about three to seven days.
Follicular phase: This phase begins on the very first day of your menstruation and will end with ovulation. The hypothalamus will prompt the pituitary gland to release follicle stimulating hormone that will then stimulate the ovary to generate about five to twenty follicles. An immature egg is housed in each follicle. Only a single follicle usually matures to become an egg as the others die. Note that this can happen at about day ten of a twenty-eight day menstrual cycle.
Ovulation: You will experience ovulation when a developed ovum is discharged from the base of your ovary. This often occurs from mid-cycle, around two or more weeks before the monthly period starts. During the follicular cycle, growing follicle will create a rise in the estrogen levels. The hypothalamus reacts to these escalating levels and will secrete gonadotrophin-releasing hormone substance. This hormone substance will stimulate the pituitary gland to generate far more luteinizing and follicle stimulating hormones. This increase in luteinizing hormone will initiate ovulation in a couple of days.
Luteal phase: The cell break away from the follicle during ovulation, but the punctured follicle will stay on the surface of the ovary. The follicle will become a corpus luteum or a framework over the next fourteen days or even more. This framework will start to expel progesterone along with small amounts of estrogen. These hormones will combine to keep the uterus wall thick and ready for the implantation of a fertilized egg cell. Once the fertilized egg cell implants in the uterus wall, it will generate hormones including the human chorionic gonadotrophin. This will continue to generate high levels of progesterone which are needed to keep your uterus wall in the thickened state.
If you are not pregnant, the corpus luteum will die around day 22 in a 28 day period. When the progesterone levels decline, this causes the uterus wall to drop apart and menstruation will take place. After that, the menstrual cycle phases will repeat.