If fertilization does not occur after ovulation: 1) The corpus luteum will degrade, stopping progesterone and estrogen production. 2) Without progesterone, the uterine lining will break down and be shed, resulting in menstruation. 3) Menstruation marks the end of the current cycle and the start of a new follicular phase under the influence of FSH.

1. What will happen if fertilization
did not occur?

2. THE MENSTRUAL CYCLE
The menstrual cycle includes
the activity of the hormones of
the ovaries and anterior
pituitary gland and the
resultant changes in the
ovaries (ovarian cycle) and
uterus (uterine cycle)

3. A cycle may be described in terms of three
phases: menstrual phase, follicular phase,
and luteal phase.
1. Menstrual phase—The loss of the functional layer
of the endometrium. Although this is actually the end
of a menstrual cycle, the onset of menstruation is
easily pinpointed and is, therefore, a useful starting
point. Menstruation may last 2 to 8 days, with an
average of 3 to 6 days. At this time, secretion of
FSH is increasing, and several ovarian follicles
begin to develop.

4. 2. Follicular phase- FSH and estrogen
promote the growth and maturation of
the ovum, and estrogen stimulates the
growth of blood vessels in the
endometrium to regenerate the
functional layer. This phase ends with
ovulation, when a sharp increase in LH
causes rupture of a mature ovarian
follicle

5. 3. Luteal phase—Under the influence of LH, the
ruptured follicle becomes the corpus luteum and
begins to secrete progesterone as well as estrogen.
As progesterone secretion increases, LH secretion
decreases, and if the ovum is not fertilized, the
secretion of progesterone also begins to decrease.
Without progesterone, the endometrium cannot be
maintained and begins to slough off in menstruation.
FSH secretion begins to increase (as estrogen and
progesterone decrease), and the cycle begins again.

7. Sexually Transmitted Diseases
Sexually transmitted diseases (STDs) are those in
which the pathogen is acquired during sexual
activity. Most are caused by bacteria or viruses.

8. Gonorrhea—caused by the bacterium
Neisseria gonorrhoeae. Infected men have
urethritis with painful and frequent urination
and pus in the urine. Women are often
asymptomatic, and the bacteria may spread
from the cervix to other reproductive organs
(pelvic inflammatory disease [PID]).
Gonorrhea can be treated with antibiotics, but
resistant strains of the bacteria complicate
treatment.

9. Syphilis—caused by the bacterium
Treponema pallidum. Although syphilis
can be cured with penicillin, it is a
disease that may be ignored by the
person who has it because the
symptoms may seem minor and often do
not last long. If untreated, however,
syphilis may cause severe or even fatal
damage to the nervous system and
heart.

10. Chlamydial infection—caused by Chlamydia
trachomatis,. Infected men may have
urethritis or epididymitis. Women often have
no symptoms at first but may develop PID,
which increases the risk of ectopic
pregnancy. Chlamydial infection can be
treated successfully with antibiotics such as
erythromycin or azithromycin.

11. Acquired Immunodeficiency Syndrome (AIDS)
caused by Human Immunodeficiency Virus
which destroys the body’s ability to fight
infection.
It can be transmitted through:
a. sexual intercourse with an infected person
b. sharing needles with an infected person
c. being born to an infected mother or drinking
the breast milk of an infected woman

12. Since it takes up to 10 years for HIV to
change a person’s immune system enough
to cause illness, a person can be infected
with HIV for many years without being aware
of it. Thus, it is important to be aware of the
common symptoms of this disease and how
it can be avoided or treated

13. Personal Hygiene
1. Take a bath daily. Clean your external
organs by washing them with soap and
water.
2. Use only clean underwear and change it as
often as necessary
3. During menstruation, girls should change
napkins as often as necessary. They should
take quick shower but should not go
swimming because it is unsanitary to do so.

14. What are the other health practices that
you follow to care for your reproductive
organs?
Write in your Science Notebook