Physiology of Menstruation

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Menstruation - is the periodic discharge of blood, mucus and epithelial cells from the uterus.

Menstrual Cycle - periodic uterine bleeding in response to cyclic hormonal changes. A process that allows for conception and implantation of new life.

It is usually determined by counting as day 1 the 1st day of a menstrual period until the last day before the next menstrual period.

Purpose:

• To bring an ovum to maturity
• To renew a uterine tissue bed that will be responsive to fetal growth
• To prepare the uterus for pregnancy

Characteristics of Normal Menstrual Cycles

TERM	DESCRIPTION
Beginning (Menarche)	average age of onset: 12 or 13 years; average range of age: 9-17 years
Interval between cycles	average 28 days; cycles of 23 to 35 days not usual
Duration of Menstrual flow	average flow: 2-7 days; ranges 1-9 days not normal
Amount of menstrual flow	difficult to estimate; average 30 to 80 ml. per menstrual period; saturating a pad in less than an hour is considered heavy bleeding.
Color of menstrual flow	dark red; a combination of blood, mucus, and endometrial cells
Odor of menstrual flow	marigold

Discomforts of Menstruation

1. Breast tenderness and feeling of fullness
2. Tendency towards fatigue
3. Temperament and mood changes - because of hormonal influence and decreased levels of estrogen and progesterone
4. Discomfort in pelvic area, lower back and legs
5. Retained fluids and weight gain

Abnormalities of Menstruation

1. Amenorrhea - absence of menstrual flow
2. Dysmenorrhea - painful menstruation
3. Oligomenorrhea - scanty menstruation
4. Polymenorrhea - too frequent menstruation
5. Menorrhagia -excessive menstrual bleeding
6. Metrorrhagia - bleeding between periods of less than 2 weeks
7. Hypomenorrhea - abnormally short menstruation
8. Hypermenorrhea - abnormally long menstruation

Four body structure involved in the physiology of the menstrual cycle:

1. Hypothalamus
2. Pituitary gland
3. Ovaries
4. Uterus

Reproductive Hormones:

1. Gonodotropin-Releasing Hormone (GnRH)
   • Stimulates release of FSH and LH initiating puberty and sustaining menstrual cycle.
2. Follicle-stimulating Hormone (FSH)
   • secreted by anterior pituitary gland during the 1st half of menstrual cycle
   • stimulate growth and maturation of graafian follicle before ovulation
   • thins the endometrium
3. Luteinizing Hormone (LH)
   • secreted by the anterior pituitary gland
   • stimulates final maturation of graafian follicle
   • surge of LH about 14 days before next menstrual period causes ovulation
   • stimulates transformation of graafian follicle into corpus luteum
   • thickens the endometrium
4. Estrogen
   • secreted primarily by the ovaries, corpus luteum, adrenal cortex and placenta in pregnancy
   • considered the Hormone of Women
   • stimulates thickening of the endometrium; causes suppression of FSH secretion
   • responsible for the development of secondary sex characteristics
   • stimulates uterine contractions
   • increases water content of uterus
   • high estrogen concentration inhibits secretion of FSH and Prolactin but stimulates secretion of LH7.
   • low estrogen concentration after pregnancy stimulates secretion of Prolactin
5. Progesterone
   • secreted  by the ovary, corpus luteum and placenta during pregnancy
   • inhibits secretion of LH
   • has thermogenic effect (increases body temperature)
   • relaxes smooth muscles thereby decreases contractions of uterus
   • causes cervical secretion of thick mucus
   • maintain thickness of endometrium
   • allows pregnancy to be maintained = Hormone of Pregnancy
   • prepares breasts for lactation
6. Prolactin
   • secreted by the anterior pituitary gland
   • stimulates secretion of milk
7. Oxytocin
   • secreted by the posterior pituitary gland
   • stimulates uterine contractions during birth and compress uterine blood vessels and control bleeding
   • stimulates let-down or milk-ejection reflex during breastfeeding
8. Prostaglandins
   • fatty acids’ categorized as hormones
   • produced by many organs of the body, including the endometrium
   • affects menstrual cycle
   • influences the onset and maintenance of labor

Other Nursing Articles you may want to look at:

• Nursing Care Plan - Dysfunctional Uterine Bleeding (DUB) Dysfunctional uterine bleeding is abnormal uterine bleeding in the absence of clinical or ultrasonographic evidence of structural abnormalities, inflammation, or pregnancy. Treatment is usually with oral contraceptives. Dysfunctional uterine bleeding (DUB), the most common cause of abnormal uterine bleeding, occurs most often in women > 45 (> 50% of cases) and in adolescents (20%
• Functions of the Female Reproductive Organs Organ Functions 1. Vagina a. Passageway of menstrual flow b. Female organ for coitus; receives male penis c. Passageway for the fetus during birth 2. Uterus a. Houses and nourishes fetus until sufficiently mature to function outside the mother’s body b. Uterine muscles propels fetus outside. 3. Fallopian Tube a. Provides passageway for ovum as it travels from ovary to uterus. b. Site of Fertilization. 4.
• Female Reproductive System A. External Structures: Mons Veneris/Pubis - Pad of fat which lies over the symphysis pubis where dark and curly hair grow in triangular shape that begins 1-2 years before the onset of menstruation. It protects the surrounding delicate tissues from trauma. Labia Majora - Two (2) lengthwise fatty folds of skin extending from mons veneris to the
• Nursing Care Plan - Endometrial Cancer Endometrial cancer is one of the most common cancers in women. Usually begins in the endometrium, the lining of the uterus — a hollow, pear-shaped pelvic organ where fetal development occurs. Endometrial cancer is most common after the reproductive years, between the ages of 60 and 70. Endometrial cancer is sometimes called uterine cancer, but
• Nursing Care Plan - Ectopic Pregnancy Ectopic pregnancy is gestation located outside the uterine cavity. The fertilized ovum implants outside of the uterus, usually in the fallopian tube. Predisposing factors include adhesions of the tube , salpingitis, congenital and developmental anomalies of the fallopian tube, previous ectopic pregnancy, use of an intrauterine device for more than 2 years, multiple induced