A Short Primer On The Physiology of the Menstrual Cycle

PART ONE
Many people, are not familiar with how the female menstrual cycle operates. In this article we will discuss it from the stand point of both Western Medicine and Traditional Chinese Medicine. First lets take a look at the Western model. It may seem a bit confusing at first but with a little effort, you should come to appreciate intricate workings of a woman's hormonal cycle.

There is a saying in TCM (Traditional Chinese Medicine) that it is easier to treat ten men than one woman. This is because of the complexity inherent in a women's monthly cycle. There are many opportunities for things to go wrong at each stage of the cycle.

The menstrual cycle is quite sensitive to stress (environmental or emotional). Problems such as PMS, infertility, or menopausal symptoms occur with great frequency in a large portion of the female population. Western medicine tries to control these imbalances with synthetic hormone combinations. This is a mixed blessing at best. These drugs are known to have side effects which range from uncomfortable to cancer. There are however, occasions where western hormone therapy might be useful for short periods of time.

The nice thing about trying to correct a problem with herbal medicine is that it often works and does so without (or with minimal) side effects. But, even when using herbal medicine, it may still take some time experimenting to find the right combination and dosage to correct the symptoms.

It is quite interesting that women in many parts of the world do not experience PMS or Menopausal symptoms, whereas in Western industrialized countries it is very common. There are of course many factors contributing to this difference such as diet, life style, and the physical environment.

It would greatly benefit any women experiencing difficulties related to her menstrual cycle to understand how diet and stress are direct contributors to those problems. For example, high amounts of carbohydrates (and sugars) will magnify PMS symptoms. There are many good books on this subject.

Two herbal products which are specific to treating female imbalances are:
1. PMS
2. MENOPAUSE

Over the years, I have given both of these formulas (with slight modifications) to my patients. I have settled on the present formulation which I find alleviates the symptoms (or even eliminates them) in about 80% of the women I treat.

In Part 2, I will discuss PMS and Menopause from both the Western and Chinese perspectives. I will also explain how the herbs in the two formulas above work to correct some of the most common symptoms associated with the menstrual cycle.

Note:
The following information has been adapted from our Homestudy course on Chinese Herbal Medicine. www.ich-herbschool.com

Menstrual Cycle - Western Description

What is Normal
28 days is considered the textbook normal cycle, but it can range between 25 and 35 days. If it is regular, it can still be considered within the normal range. In fact, some women have a period once every two or three months or even once yearly. If it comes regularly it is still considered normal in that it will not necessarily interfere with her ability to get pregnant.

Physiology of Menstruation
Lets take a look at the following glands and organs which are involved with the menstrual cycle. It might be helpful to refer to the chart below as you read about these glands and hormones.

Hypothalamus
This gland produces a hormone called GnRH (gonadotropin) which regulates the secretion of LH (leutenizing hormone) and FSH (follicle stimulating hormone). It sends GnRH to the Pituitary gland which is responsible for the release of FSH and LH. It also controls the autonomic nervous system balance and is involved in emotions and their physiologic responses.

Gonadotropins
Regulate the production of FSH which stimulates the secretion of estrogens. Also regulates the production of LH which stimulates the secretion of estrogens and progestins.

Negative Feedback Loop
A drop in estrogen production inhibits the production of FSH and LH. A increase in progestins helps lower the estrogen.

Pituitary Gland
Secretes FSH and LH These are secreted in 28 day cycles and directly affect the ovaries. FSH stimulates the growth of the follicles, the maturation of the egg and the process of ovulation. When the FSH reaches a certain point the egg is released into the fallopian tube. Ovulation usually occurs 14 days after the start of the period. But, 12-16 days is also considered normal. The basal temperature rises at ovulation time.

Ovaries
Secretes two hormones which effect the endometrium: estrogen and progesterone. Before ovulation estrogen is secreted which causes the endometrium to thicken and prepare a bed for the ovum. Progesterone is secreted which softens the endometrium and causes it to become filled with blood.

OBJECTIVES OF THE MONTHLY CYCLE
To produce an ovum and prepare the uterine endometrium for implantation and fertilization of the ovum. If not fertilization takes place, the endometrium releases the blood (menses), and the cycle starts all over again.

Hormones and the Menstrual Cycle

Estrogens
The word is derived from the Greek word estrus meaning heat, fertility or sometimes translated as ardent desire. This is referring to the ovulation period of animals.

Beta-estradiol, esterone and estriol are the main forms used by the body. They are derived from cholesterol and form a group known as Estrogens. Estriol, the main estrogen is secreted by the ovaries and produced in the liver. During pregnancy, the placenta secretes most of the estrogen. It has been found that a diminished liver function can potentiate the activity of the estrogens.

Increasing amounts of estrogens are produced after menstruation and peak just before ovulation. They then progressively diminish until menstruation.

Functions of Estrogen
1. Responsible for changes to the vaginal epithelium, uterine endometrium and the mucosal lining of the fallopian tube
2. Decrease the rate of bone breakdown and re-absorption by the body by an antagonistic effect on the parathyroid hormone. It does not actually stimulate or strengthen bones.
3. Causes fats to be deposited in the buttocks, hips and thighs
4. Enhances the coagulability of blood
5. Increases HDL and trygliceride levels
6. Lubricates the vaginal mucosa to protect against irritation during sex
7. Responsible for: changes in a girl at puberty, growth and development of vagina, uterus and fallopian tubes, enlargement of the breasts

Problems of Excess Estrogen (unopposed)
1. Can be a cause for edema by facilitating the loss of intra vascular fluid into extracellular space
2. Opposes the actions of the thyroid gland
3. Promotes histamine release
4. Increases the risk of stroke due to its promotion of blood clotting
5. Gall bladder diseases (thickens bile)
6. Decreases libido
7. Can cause abnormal bleeding
8. Increases risk of breast and endometrium cancer, fibrocystic breasts
9. Decreased amounts can contribute to osteoporosis
10. Irregular menstruation during perimenopause
11. Can cause some premenstrual symptoms due to a sudden drop (i.e. migraines, etc.)

Progesterone
The word is derived from a Greek work meaning to promote testation. Progesterone is a steroid hormone, secreted by the ovaries. The amount secreted increases during the second half of the cycle (ovulation to menstruation). At menstruation it breaks down in the uterus and liver. In pregnant woman progesterone is secreted by the placenta.

Functions
1. Promotes secretory changes in the Uterine endometrium preparing it for implantation of the fertilized ovum
2. Reduces the frequency and intensity of uterine contractions to help prevent the ovum from being expelled
3. Promotes secretory changes in the mucosal lining of the fallopian tubes in order to provide nutrition for the ovum. Plus helps support the fetus during pregnancy.
4. Increases the viscosity of the cervical mucous and decreases the amount of mucous in the cervix
5. Increases body temperature up to 1 degree F during ovulation
6. During pregnancy production increases (mostly by the placenta) to around 300-400 mg daily during the third trimester
7. Protects against: endometrial and breast cancer and fibrocystic breasts
8. Acts as a natural antidepressant
9. Aids in normal blood clotting functions (opposing estrogens blood clotting function)
10. Precursor of cortisone synthesis (by the adrenal cortex)
11. Normalizes blood sugar levels
12. Diuretic (countering the edema tendency of estrogen)

Deficiency of Progesterone
1. During the period between ovulation and menstruation it can cause behavioral changes (mood swings etc.) known as PMS due to an excess of estrogen. If there is a month without ovulation then the corpus luteum does not get produced and consequently no progesterone is made. This creates a hormonal imbalance with unopposed estrogen leading to PMS mood swings etc.
2. Morning sickness, post partum depression
3. Can be caused by a tubule ligation
4. Osteoporosis. Progesterone stimulates osteoblast-mediated new bone formation

Deficiency of the Corpus Luteum
Defined as abnormally low progesterone levels three weeks after the onset of menstruation. A low amount is considered normal at puberty and menopause.
1. Causes a decrease in ovarian functions resulting in anovulation
2. Decreases the production of progesterone resulting in mood swings or even ovarian cysts
3. Menorrhagia, metrorrhagia, polymenorrhea, amenorrhea, irregular cycles
4. Sterility

Stress
Stress can interfere with the functioning of the hypothalamus. This in turn can cause a cycle without ovulation and a lack of production of progesterone necessary to counterbalance the estrogen.

A lack of progesterone also interferes with the production of adrenal corticosteroids which diminishes our response to stress. This adds a physiologically induced stress to the situation magnifying and perpetuating the response to the situational stressful conditions.

THE THREE PHASES
1. Proliferation of the Uterine Endometrium
2. Secretory changes in the Uterine Endometrium
3. Desquamation of the Uterine Endometrium

PHASE 1 (Estrogen Phase)
The low levels of estrogen and progesterone after menstruation stimulate the hypothalamus to Send GnRH to the Pituitary gland. The Pituitary sends FSH to the ovaries which stimulates them to begin increasing their production of estrogen (mainly estradiol). At around the 10th day the high levels of estrogen signals the pituitary to produce LH for ovulation. This also promotes an increase in the layer of endometrium cells in the uterus.

After menstruation the secretion of LH rises 6-10 times higher and peaks around 16 hours before ovulation. The FSH is increased 2-3 times higher. Together they cause the rapid arisal of the follicle. There is an increase of LH which helps increase Progesterone and lowers estrogen.

By the time ovulation occurs the endometrium is 3-4 mm thick. At this time a stringy mucous is secreted which protects the sperm and helps lead it into the uterus.

PHASE 2 (Progesterone Phase)
This lasts about 12 days. It is during this time (after ovulation) that the tissue of the follicle contracts into a yellowish ball called the corpus luteum. LH secreted by the anterior pituitary stimulates the growth of the corpus luteum and prevents other eggs from maturing.

There are higher amounts of progesterone produced (about 20 mg a day) and lower amounts of estrogen. This causes a swelling of the endometrium (5-6mm) with blood about 1 week after ovulation.

The corpus luteum secretes estrogens and progestins and helps lower the levels of FSH and LH. By the 26th day of the cycle this causes the corpus luteum to degenerate and eliminated during menses.

PHASE 3 ( Menstruation Phase)
7-8 days after ovulation the corpus luteum grows turns yellowish and grows in size to around 1.5 cm. If after 10-12 days, pregnancy does not occur, there is a sudden reduction in the levels of estrogen and progesterone causing a shedding of the endometrium. During menses approximately 40 ml of blood and 35 ml of serous fluid are discharged. Estrogen and Progesterone are metabolized in the liver and excreted in bile and urine.

Fertilization. If fertilization occurs, then the corpus luteum continues to secrete progesterone which keeps the endometrium functioning as a support system for the fetus.

No Fertilization. If no fertilization takes place, then the corpus luteum turns yellow and no longer secretes progesterone. This ends the support for the endometrium and the blood which was meant to support the fetus is discharged as menstrual blood.

Note: too much estrogen can cause mid-cycle bleeding since it causes the blood vessels in the endometrium to grow too big and too fast. This bleeding will stop when the level of estrogen drops and the secretion of progesterone begins.

14 yr. old The Ren Meridian is open and the Chong Meridian fills up. Menstruation begins and the girl can become pregnant.
21 yr. old The Kidney Qi is stable and the Yang Ming meridians are full of energy. The face has the beauty of youth.
28 yr. old Even after having children, a woman's tendons and bones are strong and her body still flourishes.
35 yr. old The energy in the Yang Ming meridians begins to decrease and the youthful brightness leaves the face.
42 yr. old The Kidney Qi is decreasing and her hair begins to turn white.
49 yr. old The Ren and Chong meridians and the Tian Gui (reproductive organs including the Uterus) are now deficient. Menstruation ends. Organ systems involved in Menstruation slow down.

As you will discover, the Chinese have described the female system and cycle in a more energetic manner rather than western scientific. The system is consistent with treatment therapies such as acupuncture and herbs. When an organ name is used (such as Kidney or Liver), it does not have the same meaning as in western medical science. It is a system that describes how the energetics of the organ works and the areas it influences.

One of most defining differences between TCM and Western medicine is the Chinese description of the meridian system. This is like a net work of wiring in which current flows to every part of the body. Any problems in the amount available or its ability to flow freely will result in varying degrees of imbalances. Over time this can result in disease and/or pain.

You might want to review the functions of Yin, Yang, Qi and Blood. There are pages on the internet which explain these. Do a search on one of the terms, using a search engine like Google. Put in terms such as: Chinese Medical Theory or Acupuncture. Or order the "Introduction to Chinese Medicine" from the Institute of Chinese Herbology for a complete explanation of the system. www.ich-herbschool.com

Bao Gong - Uterus
Considered one of the extra-ordinary organs. The Bao Gong functions as both a zang and fu organ. Like a zang organ it "stores"- blood before conception and a fetus after conception. As a Fu organ it expels blood during menstruation and a baby at birth. The Bao Gong also stores the Jing essence (a very refined Qi which is responsible for sexual energy and human development). Also a connecting area for the heart and kidneys.

Bao Luo Connecting vessels surrounding the Uterus which supply it with Kidney Jing and Heart Yin

Bao Mai/Chong Mai The channel which conveys the heart Qi and blood and the Kidney Yin and Yang to the uterus. Tian Gui? Heavenly Primordial Qi. (or liquid) Arrives at 14 yr. old and departs at 49 yr. of age. The Jing produced is stored until about 14 yr. when the girl has produced an abundant amount, enough to fill the Ren Mai and Tai Chong channels and create a excess of blood which begins to flows monthly as menstruate. Menopause occurs with the weakening of the spleen and kidney qi and the subsequent lack of excess blood.

The following three channels originate in the Uterus.

Chong (penetrating) meridian The Sea of Blood and all 12 meridians and is a source of nourishment for all the channels throughout the body.

Ren (conception vessel) meridianThe Sea of Yin. Controls the Bao gong, governs the Yin of the body and is responsible for conception.

Du (governing vessel) meridian The Sea of Yang. Controls the build up of yang premenstrually, which is released via the Ren Mai.

Dai Mai (girdle) meridianEncircles the Lumbar region and ties the above three meridians together and regulates the flow of Qi and blood between the upper and lower parts of the body

Production of Blood

Spleen, Kidneys, Heart - Produce blood Kidney Jing is the prenatal substrate for blood. The Spleen creates blood post-natally from the pure essence of food and liquids. The "Yuan Qi" of the kidney acts as a catalyst on the Spleen "Gu Qi" and mixes in t e upper burner with "Zong Qi". The Heart turns it red and moves it downwards.

Liver Stores the blood (Yin and Jing) and controls the flow of Qi and so promotes the smooth release of menstruate each month. The source of pre-natal in a woman. (Kidneys are the source in a man).

The Menstrual Cycle
When a women reaches 14 years of age, her Kidney water fills and overflows. This allows the Ren meridian to open fully and flow. The normal cycle is 28 days (25-35 is also normal). Menstrual discharge lasts 3-5 days (up to 7 days is in a normal range). The volume of blood for a "virgin" is 50-100 milliliters. The volume increases in sexually active women.

The color should be light at the onset and darken over the next few days. The discharge should be free of clots or odor and not be watery or sticky. Some slight soreness or distension in the lumbar or lower abdomen is normal before the onset and should disappear once the period begins.

TCM defines four stages (Western medicine describes 3 stages in the menstrual cycle)

1. Post Menstruation
The over filled uterus discharges and the Chong Mai becomes empty. There is a relative deficiency of blood and yin. Blood and Yin begin to replenish.

2. Mid-Cycle
Ovulation marks the transition of Yang to Yin. The blood and yin are back to normal amounts. The Yang Qi begins to grow. Blood begins to fill the uterus.

3. Pre-Menstruation
The continued growth of Liver and Kidney Yin. They reach their maximum and the body becomes more hot. (Increase of basal temperature). The Liver now fills the Ren and Chong Mai until an overflowing is reached (Menstruation).

4. Menstruation
The smooth flow of blood is dependent upon the unimpeded flow of Liver Qi. (the yang aspect of the liver).

Yin, Yang and the Menstrual Cycle
The Tai Chi symbol illustrates the dynamic interplay of Yin (white) and Yang (black). Yang begins as the Yin peaks and gradually increases .