Saturday, June 7, 2008

The Menstrual Cycle



The "typical" menstrual cycle occurs regularly over 28 days. Most women have cycles with an interval that lasts from 21 to 35 days. Frequently cycles are unusually short or long during adolescence.


THE FIRST HALF OF THE MENSTRUAL CYCLE (Day 1 to About Day 14 in a 28-Day Cycle)
The Menstrual PhaseThe first day of your menstrual period is considered Day 1 of your cycle. The menstrual phase includes your period. During this time, the endometrium (the built-up lining of the uterus) is shed, along with a little blood. Many of the problems that women experience with their menstrual cycle occur during this phase. For example, some women experience menstrual disorders such as dysmenorrhea (painful periods) or menorrhagia (unusually heavy periods).
The Follicular/Proliferate PhaseDuring the proliferate phase, the body produces a hormone called follicle-stimulating hormone (FSH). Follicle-stimulating hormone promotes the growth of a follicle (egg sac) within the ovary. An ovum (egg) matures in the follicle during the proliferative phase. FSH also stimulates the ovary to produce increasing amounts of estrogen. In turn, the estrogen causes endometrial tissue to build up (or proliferate), lining the interior of the uterus.
THE MIDPOINT OF THE MENSTRUAL CYCLE (About Day 14 in a 28-Day Cycle)
The mature ovum bursts from the follicle about midway (approximately 2 weeks before onset of next menstrual period) through the menstrual cycle. This process is known as ovulation. The ovum then travels from the ovary down the fallopian tube, and into the uterus.
The Luteal/Secretory PhaseOnce the ovum has been released, the follicle becomes a sac known as the corpus luteum ("yellow body," because it contains yellowish, fatty matter). A hormone called luteinizing hormone (LH) causes the corpus luteum to grow and to secrete progesterone, another female hormone.
During the secretory phase, progesterone makes the endometrial lining stronger and spongy in texture. Progesterone also stimulates glands in the endometrium. These glands produce uterine fluid, and their purpose is to support embryonic development if fertilization has occurred at or around the time of ovulation. It is in this phase of the menstrual cycle that women who suffer from premenstrual syndrome (PMS) may begin to experience their symptoms. Generally symptoms are worse during the last seven to ten days of the cycle, ending at or soon after the start of the menstrual period. In a woman who hasn't become pregnant, the level of progesterone peaks about a week after ovulation and then begins to drop along with the estrogen level. The flow of blood to the endometrium decreases, and its upper portion is broken down and shed during menstruation. At the same time, the corpus luteum withers.
The dip in estrogen and progesterone at the end of the cycle help let the body know that it's time to start the cycle all over again. The menstrual cycle doesn't have to be a drag, it actually shows how complex your body is and a sign that it is functioning properly! Congratulations, you are a woman and being a woman is terrific!


The Charts
The Ovarian Cycle chart shows the maturation and deterioration of the ovum and how it occurs every month.

The Endometrial Cycle chart shows how the endometrial lining builds up during the normal menstrual cycle and then is broken down and shed during menstruation (menses). Meanwhile at the same time back at the Ovarian Cycle chart, the corpus luteum withers.

Aren't women amazing! The menstrual cycle is actually a very cool and very complex process that results from the many parts of the body working together. The brain, the ovaries, the adrenal glands, and even the thyroid all have to come together with their different hormonal and chemical influences. I guess you could say it is kind of like a small orchestra in your body.

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