BATAAN PENINSULA STATE UNIVERSITY
COLLEGE OF NURSING AND MIDWIFERY
City of Balanga 2100 Bataan
PHILIPPINES
Topic # 2 – PHYSIOLOGY OF MENSTRUAL CYCLE
Female Reproductive Cycle – refers to the regular and recurrent changes in the secretion of anterior
pituitary gland, ovary and uterine endometrium that are designed to prepare the body for pregnancy. It is
often called menstrual cycle because menstruation provides a marker for each beginning and end if
pregnancy does not occur. The duration of cycle is about 28 days though it may range from 20-45 days.
During puberty, a weight of 95lbs or 43kgs, triggers the initiation of menstrual cycle
Ultimate initiator of menstrual cycle
Hypothalamus
FSHRF
LHRF
APG
FSH
LH
OVARIES
ESTROGEN
PROGESTRERONE
UTERUS
I.
BODY STRUCTURES
A. HYPOTHALAMUS
The hypothalamus is the ultimate initiator of the menstrual cycle. By secreting the Gonadotropin
Releasing Hormones (GnRH) it governs the ovary in the same manner. The GnRH are:
• Follicle stimulating Hormone Releasing Factor (FSHRF): this hormone is triggered by low serum
estrogen level, it stimulates the anterior pituitary gland to release follicle stimulating hormone.
• Luteinizing Hormone Releasing Factor (LHRF): this hormone is triggered by low serum
progesterone level; it stimulates anterior pituitary gland to release luteinizing hormone (LH)
B. ANTERIOR PITUITARY GLAND
In response to the stimulation from the hypothalamus and low serum estrogen and progesterone levels,
the anterior pituitary gland releases the following gonadotropin hormones (GH):
• Follicle stimulating Hormone (FSH) Triggered by FSHRF and low serum estrogen. It stimulates
the development of several Graafian follicles in the ovary and the production of estrogen.
•
Luteinizing Hormone (LH) Triggered by low serum progesterone and LHRF. It stimulates corpus
luteum to produce progesterone and some estrogen. It is also the responsible for ovulation.
C. OVARIES
The ovary, known as the female gonads, produces estrogen during the first half of the cycle and
progesterone during the second half of the cycle.
•
Estrogen: FSH stimulates the Graafian follicle to produce estrogen. There are actually three kinds
of estrogen: Estradiol, Estrone and Estriol. Of these: Estradiol is the most potent and Estriol is the
one found in urine. Estrogen is metabolized by the liver and excreted in the urine.
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The effects of estrogen include:
❖ Inhibit follicle stimulating hormone.
❖ Estrogen is known as the "Hormone of Women" because it is the hormone that stimulates the
development of the female secondary characteristics such as the increased deposition of fat in
certain areas of the body that gives a female shape , breast growth, development of the
female reproductive organs and pattern of hair growth in the vulva.
❖ Stimulate proliferation of cells in the endometrium resulting in endometrial thickening.
❖ Causes mucus to be thin, transparent, and highly stretchable.
❖ Stimulates the growth of ductile structures of the breasts.
❖ Menarche and menstruation.
•
Progesterone: LH stimulates the Corpus Luteum to produce progesterone. Its byproduct, found
in the urine, is known as Pregnanediol.
The effects of progesterone are:
a. Thermogenic effect, increases basal body temperature.
b. Relaxes uterine muscles.
c. Promotes growth of the acini cells of the breasts.
d. Causes weight gain by promoting fluid retention.
e. Is thought to be the cause of Premenstrual Syndrome (PMS).
f. Causes tingling sensation and feeling of fullness in the breast before menstruation.
g. Secretory changes in the endometrium: stimulates endometrial glands to secrete mucin and
glycogen in preparation for implantation.
Prostaglandin – oxygenated fatty acids that are produced by cells of endometrium.
• PGE – relaxes smooth muscle, vasodilator
• PGF – vasoconstrictor and increases contractility of arteries and muscle
D. UTERUS
The changes that occur in the uterine endometrium are due to the influence of the ovarian
hormones: estrogen and progesterone.
• Menarche refers to the very first menstruation, an event that signifies the end of puberty and the
beginning of the reproductive years of a woman.
• The average age at which menarche occurs is 12 to 13 years, but the onset of menstruation may
occur anytime between 9 to 17 years old depending on many conditions including nutrition,
heredity, and race.
• Often occurs between the appearance of pubic and axillary hair, and approximately two after
Thelarche. The first menstrual cycles are usually anovulatory, painless and irregular.
THE OVARIAN CYCLE
TWO PHASES:
I. FOLLICULAR PHASE (1-14 days) - varies
➢ The immature follicle (primordial follicle) matures as a result of FHS & small amount of LH. The
blood levels of estradiol in blood stream begin to rise & estradiol in turn acts negatively on the CNS
at the hypothalamic-pituitary level by inhibiting the release of additional FHS. Consequently, the
levels of FHS in circulating blood begins to fall.
➢ Few days prior to ovulation, all but one follicle that is destined to ovulate begin to regress or
degenerate (ATRESIA), forming atretic follicle
Growth of a Follicle is characterized by:
1. Proliferation of granulose
2. Formation of a capsule connective tissue from the ovarian stroma around the follicle (consisting of
a connective of an inner cellular layer, the theca interna, and outer fibrous layer, the theca externa).
3. Completion of the first metiotic division with the formation of secondary oocyte
4. Expulsion of the follicular content.
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CNS
↓
Hypothalamus
↓
FSHRF
↓
APG
↓
FHS
↓
Ovaries
↓
Immature follicle
↓
Mature follicle
↓
Estrogen
↓
High level of estrogen will trigger the Hypothalamus to stop releasing FSHRF,
and the APG to stop releasing FSH
↓
Decreased FSH will cause the remaining follicles to degenerate/ regress (Atresia), and they are called
atretic follicle.
As the follicle develops, a cavity (Antrum) soon appears separating the mass of proliferating cell into
2 parts. The cavity is filled with fluid (Liquor Folliculi) believed to be secreted by the cells of the
follicle. Oocyte becomes pressed to one side of vesicular follicle and is separated from the surrounding
layer of cells by a transparent membrane known as the Zona Pellucida (Oolemma).
A mound of cells surrounding the oocyte (Cumulus Oophorous) projects into the antrum. The follicle
becomes distended by an accumulation of fluid and moves outward to the surface of ovary. Once a
month, usually at the middle of 28 day cycle, the process of ovulation occurs. The follicle ruptures and
the secondary oocyte surrounded by a ring of granulose cells called Corona Radiata slowly oozes out
of the ovarian surface. (Cause of rupture is the increase in ditensibility and reduction in breaking
strength of follicular wall – theca externa – due to the secretion of progesterone by follicular tissue
which induces the production of an enzyme Collagenase)
Ovulation is initiated by a steep rise in the release of LH. It takes place following the very rapid growth of
follicle as the sustained high level of estrogen falls & progesterone secretion begins.
Occasionally, ovulation is accompanied by mid-cycle pain (Mittelschmerz) which is caused by
a thick Tunica Albuginea or by a local peritoneal reaction to the following to the expelling o
follicular content.
II.
LUTEAL PHASE (15-28 days) – fixed
➢ Begins when the ovum leaves its follicle. Under the influence of LH, the corpus luteum develops
from the ruptured follicle.
➢ First, there is minimal hemorrhage into the ruptured follicle, forming a blood clot (Corpus
Hemorrhagicum). Then a cell of ruptured follicle undergoes alteration and creates a mass known
as the Corpus Luteum which becomes yellowish after 2-3 days. The Corpus Luteum absorbs the
Corpus Hemorrhagicum. Corpus luteum secretes large amount of progesterone & lesser amounts
of estrogen.
➢ If the ovum is fertilized & implants in the endometrium, the fertilized egg begins to secrete HCG
which is needed to maintain corpus luteum. The corpus luteum provides progesterone to maintain
the pregnancy until the month the placenta takes over it.
➢ If fertilization does not occur, within about a week after ovulation, the Corpus Luteum begins to
degenerate, eventually becoming a connective tissue scar called Corpus Albicans (white scar).
With degeneration comes a decrease in estrogen & progesterone. This allows for an increase in LH
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& FHS which triggers the hypothalamus approximately 14 days after ovulation (in a 28 day cycle )
menstruation begins.
Corpus Hemorrhagicum
↓
Absorbed by corpus luteum in 2-3 days
↓
There will be an increased progesterone and decreased estrogen
_________________________________________l_______________________________________
↓
↓
Fertilization
No fertilization
↓
↓
Trophoblast cells of fertilized egg
Corpus Luteum will last for only 1-7 days
↓
↓
Human Chorionic Gonadotrophin
It will degenerate & become Corpus Albicans
↓
↓
HCG will prolong life of Corpus Luteum
Decrease estrogen & decrease progesterone
(Luteal Rescue)
↓
↓
Will trigger the CNS to start the cycle again
Corpus Luteum will secrete progesterone until 3- 4months
of pregnancy until placenta matures enough to take its place
↓
Progesterone will keep the uterus relaxed until the pregnancy reached its term
OVULATION
➢ Normal process of discharging a mature ovum from an ovary approximately 14 + 2 days prior to
onset of menses.
SIGNS OF OVULATION
1. Mittelschmerz – pain in the lower abdomen left at the side of the ovary that released the ovum
2. Spinnbarkheit – characterized by cervical mucus that is thin, watery or transparent & highly
stretchable. When dried & viewed under a microscope, the mucus reveals a fern pattern.
3. Amount of cervical mucus increases.
4. Increase BBT – 0.3 to 0.6 °C, 24-48 hours after ovulation due to the effect of progesterone
5. Mid-cycle spotting maybe present
6. Peak blood level LH 24-48hrs before ovulation, can be detected in urine test.
MENSTRUATION
➢
➢
➢
➢
➢
Is cyclic uterine in response to cyclic hormonal changes.
Occurs when the ovum is not fertilized & begins about 14 days after ovulation in 28 day cycle.
Average duration of menses 2-8 days
Average blood loss 25 – 60 ml, average 30 ml
Average iron loss 0.4 – 1 mg/day
MENSES/ MENSTRUAL FLOW
• Menstrual discharge is composed of blood mixed with cervical & and vaginal secretions, bacteria,
mucus, leukocytes and other cellular debris.
MENARCHE – refers to very first menstruation
• Average age of onset is 12 – 13 years but may occur any time between 9 -17 years old
• Ovulation does not occur in early menstrual cycle (anovulatory cycles) which are irregular in
frequency, amount of flow & duration
Factors Affecting Menstruation Cycle
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1. Emotional factors ( stress, anxiety )
2. Physical factors
3. Environmental factors
4 PHASES OF THE MENSTRUAL CYCLE
1. Menstrual Phase (1-5 days )
• Unless the ovum is fertilized, the corpus luteum is short lived. The endometrial lining is
destroyed & is rebuilt for the next possible implantation. Some endomentrial areas are shed
while others remain.
• Estrogen level is low
• Viscous & opaque
2. Proliferative Phase (6 – 14th )
• Otherwise known as follicular, estrogenic, post menstrual phase
• Enlargement of endometrial glands which becomes twisted & longer in response to increase
estrogen.
• Blood vessels become prominent and dilated
• Endometrium increases in thickness to eightfold.
• Cervical mucus shows increase elasticity
• Cervical mucosa pH increase from below 7 – 7.5 at the time of ovulation
• On exam, mucus shows ferning pattern
• Estrogen peaks just before ovulation
• Body temperature drops prior to ovulation then at ovulation BBT increase
• Mittelschmerz and midcycle spotting occurs
After menstruation, the endometrium is thin
↓
Decreased estrogen
↓
Will trigger the hypothalamus
↓
Release of FSHRF
↓
Stimulate the APG
↓
Release of FSH
↓
Stimulate the ovary
↓
Maturation of the graafian follicle
↓
Estrogen production
↓
Causes increase blood flow to the uterus
↓
This will cause an eight-folds increase in thickness of the endometrium,
Increase in mucus production which is thin and elastic,
Ferning pattern of mucus under a microscope due to increased sodium chloride.
3. Secretory Phase (14 – 26 days)
• Also called pre-gestational, luteal phase
• After release of ovum, estrogen level drop, progesterone level increases
• Endometrium goes light cellular growth, glands hypertrophy and takes on coiled and tortus
appearance which further thickens endometrium
• Glands secrete small quantitative of endometrium fluid in preparation for fertilized ovum
• Vascularity of the entire uterus increase providing a nourishing bed for fertilized ovum.
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•
If implantation occurs the endometrium under the influences of progesterone continue to
develop and become thicker, fertilize ovum begins to secrete HCG and maintain corpus luteum
Graafian follicle continues to secrete estrogen, so the estrogen reaches its highest level
Triggers the hypothalamus to:
Stop the production of FSHRF
Start to produce LHRF
Triggers the APG
Release LH
Triggers ovulation
Corpus luteum
Will produce increased progesterone
Uterine endometrium becomes corlscrew appearance, twisted,
dilated, rich in glycogen & protein, & becomes a rich spongy velvet
A mature endometrium has 3 strata or layers:
1. Functional or compact layer
2. Intermediate or spongy layer
3. Basal or inactive layer
If there is fertilization:
If there is no fertilization:
Implantation
Corpus luteum will last for only
1-7days, releasing progesterone
Trophoblast cells secrete HCG
Luteal rescue from 1-7 days up to 3-4 months
until placenta is mature enough to take its place
No HCG,
will degenerate after 1-7 days,
will become: Corpus Albicans
Corpus luteum continues to secrete progesterone
Progesterone level drops
At 3-4 months of pregnancy, trophoblast will decrease
HCG production, causing corpus luteum to degenerate
Placenta will be the one to secrete progesterone until the end of pregnancy
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4. Ischemic Phase (27 – 28 days )
• Also called premenstrual phase
• If implantation does not occur, corpus luteum decrease in function activity, degenerative
changes are observe in uterine endometrium and ischemic phase begins
• Both estrogen and progesterone level falls
• Spinal arteries undergo vasoconstriction
• Endometrium becomes pale
• Small blood vessels rupture
• Blood escapes into uterine stromal cells
Corpus luteum degenerates
Decreased estrogen and progesterone
Release of prostaglandin and endothelin-1
Vasospasm of artery and contraction of the myometrium
Ischemia
Sloughing off of the two upper layers of the endometrium
Menstrual phase.
CHARACTERISTICS OF A NORMAL MENSTRUAL CYCLE
– average age ranges from 9 -17 years
– average 28 days, may vary from 23 – 35 days
– average 2-7 days, ranges from 1 -9 days
– Difficult to estimate; average is 30 – 80 ml /menstrual period;
saturating a pad in less than one hour or consuming more than 8
perineal pads a day is considered heavy flow.
Color of menstrual flow
– dark red; a combination of blood, mucus, and endomentrial cells
Odor
– similar to that of marigolds
Average iron loss – during menstruation is 12 – 29 mgs
• A woman loses 10 -20 liters of blood in her entire life due to menstruation
Beginning (menarche)
Interval Between Cycles
Duration of menstrual flow
Amount of menstrual flow
EDUCATION ABOUT MENSTRUATION
1. That Deodorants and increased absorbency that manufacturers have added to sanitary napkins and
tampons may prove harmful.
2. Bathing/perineal Care
3. Wipe from front to back.
ASSOCIATED MENSTRUAL CONDITION
1. Hypomenorrhea - short duration of menstrual flow
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2.
3.
4.
5.
6.
7.
8.
9.
Hypermenorrhea - long duration of menstrual flow
Oligomenorrhea - irregular interval more than 40 days
Polymenorrhea - regular, irregular, interval of less than 22 days
Menorrhagia - excessive amount, duration, regular
Metrorrhagia - normal amount, irregular
Menometrorrhagia - excessive amount, duration, irregular
Intermenstrual Bleeding - occurs between regular menstrual cycle.
Amenorrhea - Absence of Menses may be due to:
a. Hypothalamic dysfunction
b. Pituitary dysfunction
c. Ovarian failure
d. Anatomic abnormalities
10. Dysmenorrhea - Painful menstruation
a. Primary- cramps with no underlying disease, uterine ischemia, normally disappears after first
pregnancy
b. Secondary- associated with diseases like endometritis, PID, Cysts,
11. Premenstrual Syndrome - symptom complex associated with the luteal phase of the menstrual cycle,
occurs between ovulation and onset of menses.
MENOPAUSE
- Refers to the time when menses cease, marking the end of reproductive abilities. Also called
Climacteric or change of life.
PREMATURE MENOPAUSE - occurs before age of 45, can be caused by surgical removal of ovaries
(oophorectomy), removal of uterus (hysterectomy), and radiation
PERIMENOPAUSE - period of time prior to menopause during which the woman move from normal
ovulatory cycle to cessation of menstruation.
- characterized by decreased ovarian function and unstable endocrine physiology,
and highly variable, unpredicted hormone profile.
A. PHYSICAL CHANGES ASSOCIATED WITH MENOPAUSE
1. Changes in the Reproductive System
2. Vasomotor Changes
Hot Flashes - feeling of heat arising from chest and spreading to neck and face usually accompanied
by night sweats, dizzy spells, palpitations, and weakness.
3. Changes in Musculoskeletal System and Skin
Osteopenia - low bone mass
Osteoporosis - bone mass decrease below critical point
Wrinkles - is due to decrease protein from skin and supportive tissues
Weight gain
4. Changes in Cardiovascular System
B. NEUROLOGIC - Alzheimer associated with high cholesterol level
C. PSYCHOLOGIC 1. Mood Swings
2. Depression
3. Despair, Irritability
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Decreased FSH
Cessation of estrogen production
Ovary
Uterus
Fallopian Tube
Cervix
No follicle
atrophy
atrophy
decreased secretions
Atrophy
absence of doderlein bacilli
Alkaline ph
Vagina
_________ _______
decreased secretions
vulvar atrophy
dry
painful coitus & irritation
Risk for infection
MANAGEMENT OF PATIENTS EXPERIENCING MENOPAUSAL SIGNS AND SYMPTOMS
1. Hormone Replacement Therapy
2. Prevention And Treatment Of Osteoporosis
a. Biphosphonates- calcium regulators
b. Selective estrogen reception modulators
Example: Raloxifene (EVISTA) - acts like estrogen by protecting the body against osteoporosis but
does not stimulate uterine or breast tissue.
c. Salmon Calcitonin- is a calcium regulator that may inhibit bone loss and is approved for use to treat
osteoporosis in women who are five years post menopause.
3. Alternative Therapy
a. Diet
Phytoestrogen- naturally occurring plant sterols that have an estrogen like effect.
Example: ginseng, agnus castus, beth root, black cohosh, dong quai, fenu greek, licorice, red sage,
sarsaparilla, wild Mexican yam, soy beans.
4. Screening for osteoporosis, CV disease, and CA
a. Osteoporosis - DEXA ( Dual Energy X-ray Absorptionmetry)
b. CV- BP, Blood Cholesterol
c. Cancer - Mammogram, pap smear, pelvic exam, digital rectal exam.
5. Lifestyle modification
a. Kidney stone prevention- liberal fluid intake 3000 ml per day
b. Prevent CV disease
c. Prevent CA
d. Contraception-possible to get pregnant, 12 months after the last menses
6. Lubricants for dyspareunia
7. Hot flashes- avoid hot environment, cooling technique
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