What Happens During the Menstrual Cycle?
Females of reproductive age experience cycles of hormonal activity that repeat at about one-month intervals. With every cycle, a woman's body prepares for a potential pregnancy, whether or not that is the woman's intention. The term menstruation refers to the periodic shedding of the uterine lining. (Menstru means "monthly.'') From which the name has derived from, “Menstrual Cycle”. The average menstrual cycle takes about 28 days (may change according to the woman ) and occurs in 3 specific phases: the follicular phase, the ovulatory phase (ovulation), and the luteal phase.
There are four major hormones involved in the menstrual cycle: follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone.
The Follicular Phase of the Menstrual Cycle
The Follicular phase takes place on the very first day of a girl’s period. During this phase the following events occur:
The brain releases follicle stimulating hormones (FSH), and luteinizing hormone (LH), which travel through the blood, to the ovaries.
As a result these hormones stimulate a growth of about 15 to 20 eggs in the ovaries. Each egg grows in its own “shell” called a follicle.
These two hormones (FSH and LH) also trigger an increase in the production of the female hormone estrogen.
As the amount of estrogen rises the production of follicle comes to an end. These hormones are carefully balanced allowing the body to limit the number of follicles that mature.
As the follicular phase develops, one of the 15-20 follicles becomes dominant and matures (this follicle is chosen at random). The other follicles stop growing and die, as the dominant follicle suppresses all of the other follicles.
The dominant follicle continues and produces estrogen.
Ovulatory Phase of the Menstrual Cycle
The ovulatory phase, or sometimes known as ovulation, starts about half way through the menstrual cycle (14 days after the follicular phase started). During the ovulatory phase, the following events occur:
An increase in the amount of the luteinizing hormone that is produced by the brain is triggered by the rise of estrogen levels.
As a result the dominant follicle release its egg from the ovary. As the egg is released ovulation takes place. The egg is captured by finger-like projects that help transport the egg through the fallopian tube. The fimbriae then sweeps the egg into the tube.
There is an increase in the amount and thickness of mucus produced by the cervix during this phase. If a woman had intercourse during this period, the thick mucus lining captures the man’s sperm, nourishes and helps it to move forward towards the egg for fertilization. Without mucus, the sperm wouldn’t be able to reach the egg, and to fertilize the egg.
Luteal Phase of the Menstrual Cycle
The luteal phase is the last phase of the menstrual cycle, and begins right after ovulation, and it involves the following processes:
The empty follicle develops into the corpus luteum
Progesterone is secreted by the corpus luteum. The function of Progesterone is to prepare the uterus for a fertilized egg to implant itself in the lining of the uterus. (If sexual intercourse has taken place)
If intercourse has taken place at this stage, and a man’s sperm has fertilized the egg (a
process called conception), the fertilized egg (which eventually becomes an embryo/fetus) will travel through the fallopian tube to implant itself in the uterus. The woman is now considered pregnant.
If the egg is not fertilized by a man’s sperm it passes through the uterus, not needing to support pregnancy the lining of the uterus breaks down and sheds. (The woman actually gets her “period”.)
The length of the actual “period” may be between 4 days and 2 weeks.
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