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Lecture 3

Menstrual Cycle

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Objectives

On completion of this part, the student will be able to:

Define each vocabulary and term listed
Identify the male reproductive organs
Explain the menstrual and ovarian cycles
List the functions of the male hormone testosterone

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Role of testosterone at puberty

In male:

Further development of the external and internal reproductive structure
Appearance of pubic, axillary, and facial hair
Laryngeal enlargement
Maturation of spermatozoa
Closure of growth of long bones

In female:

Influence enlargement of the labia majora, clitoris
Formation of axillary and pubic hair

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Menstruation

Episodic uterine bleeding in response to cyclic hormonal changes

Characteristics of normal menstrual cycles:

Menarche: onset, average 11-13 yrs; may range 9-17yrs
Interval: average 28days, may 23-35 days
Duration: average 4-6 days, may 2-7 days
Amount: 30-80 ml per cycle, saturating pad within 1 hrs is heavy bleeding
Color: dark red (blood, mucus, and endometrial cells)
Odor: similar to that of marigolds

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Physiology of menstruation

4 body structure involved

Hypothalamus
Pituitary gland
Ovary
Uterus

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Menstruation :Hypothalamus

Release gonadotropin-releasing hormone (GnRH) (also called luteinizing hormone-releasing hormone (LHRH))
Signal the anterior pituitary gland
Repressed by high estrogen levels (also inhibited by prolactin, FSH, LH)

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Menstruation :Pituitary gland

produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH) under the effect of GnRH
FSH: active early in the cycle, responsible for maturation of the ovum
LH: active at the midpoint of the cycle, responsible for the ovulation, growth of the uterine lining

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Menstruation: Ovary

FSH: stimulates primordial follicles in the ovary to grow and mature
As follicles grows it produce follicular fluid (clear) that contain high content of estrogen and some progesterone
At full maturity: it is visible, .25-.5 inches, contain a barely visible ovum
Graafian follicle: is the ovum, follicle and fluids altogether
By 14 dayes: ovum divide into primary oocyte (contain the bulk of cytoplasm) and secondary oocyte by mitotic division and meiotic division (23 chromosome)

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Cont. Menstruation: Ovary

LH: on 14^th day: prostaglandins released and ruptured the follicle so the ovum is set free (ovulation) and enter the fallopian tube
LH influence the follicle after the ovum out and make it begin to produce lutein (yellow fluid rich in progesterone with some estrogen)
The follicle now called corpus luteum (yellow body)

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Cont. Menstruation: Ovary

Body temperature rise 1°F (.5 °C) on the day after ovulation
If conception occur the corpus luteum remains until 16-20 wks
If not: the unfertilized ovum atrophies after 4-5 days and the corpus luteum remain 8-10 days and it gradually replaced by white fibrous tissue (corpus albicans, white body)

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Menstruation: Uterus (4 phases)

Proliferative phase
Secretory phase
Ischemic
Menses

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Proliferative phase (1^st phase)

In the first half of the cycle (from days 5-14)
As the ovary begins to produce estrogen, the endometrium begins to proliferate (multiply) rapidly and increase in thickness approximately 8 fold.

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Secretory phase (2^nd phase)

After ovulation
Under the effect of progesteron
Endometrium become twisted in appearance and dilated with quantities of glycogen and mucin (protein)
Endometrial capillaries increase in amount until the lining become rich spongy velvet.

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Ischemic (3^rd phase)

Fertalization does not occure
Corpus luteum regress after 8-10 days
As it regress, estrogen and progesterone levels decrease and their stimulation withdraw
Endometrium, begins to degenerate (day 24-25)
Capillaries rupture, with minute hemorrhages and the endometrium sloughs off

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Menses (4^th phase)

1^st day of menses is the begning of the new cycle
Iron loss is 11mg during menses
Products of the menses blood:
Blood
Mucin
Fragments of endometrial tissue
The atrophied ovum

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Cervical mucus

1^st half of cycle: mucus thick and scant
Time of ovulation: mucus are thin and copious
2^nd half of the cycle: mucus become thick

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Menstrual irregularities or menstrual problems

1. Amenorrhea occurs when a woman does not get her period by age 16, or when she stops getting her period for at least three months and is not pregnant.�

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Possible causes can include:

moderate or excessive exercising,
eating disorders (such as anorexia nervosa),
physical or psychological stress,
tumors,
hormonal problems.
women with polycystic ovary syndrome (PCOS) may also experience amenorrhea.��

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Treatment for amenorrhea depends on the underlying cause.
Sometimes lifestyle changes can help if weight, stress, or extreme physical activity is causing the amenorrhea.
Other times, medications and oral contraceptives can help the problem.� �

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2. Oligomenorrhea

infrequent menstrual periods, or having a period only now and then.
oligomenorrhea is not a disease itself, but is a symptom of a larger condition. For example, many women with polycystic ovary syndrome (PCOS) have oligomenorrhea.��

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3. Premature Ovarian Failure (POF)

a stop in the normal functioning of the ovaries in a woman younger than age 40.
Women with POF may not have periods or may get them irregularly.
Although getting pregnant is difficult for women with POF, it may still be possible.� ��

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4. Dysmenorrhea

Dysmenorrhea refers to painful periods, including severe menstrual cramps.
The condition is usually not serious, although it can sometimes be caused by infection, endometriosis, or ovarian cysts.� � ��

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