468 Chapter 19
Common Disease, Disorder, or ConditionCervical CancerCancer of the cervix is a slow-growing cancer that is common in women who are
between the ages of 30 and 50. Conditions that can lead to the development of this type
of cancer include frequent sexual intercourse with multiple sex partners, sexu-ally
transmitted diseases (e.g., gonorrhea and syphilis), frequent cervical inflamma-tion, and
multiple pregnancies. Yearly Pap smear tests are significant factors in early detection
and treatment of this type of cancer.( KOR - pus hem - oh - RAJ - ih - kum). This clot is
eventually absorbed by the remaining follicular cells.
Eventually these cells enlarge, change structure, and form
the corpus luteum or yellow body.
The postovulatory or secretory phase. This phase is the
most constant in duration and lasts from days 15 to 28 in
our 28-day cycle. It represents the time between ovulation
and the onset of the next menstrual cycle. After ovulation
occurs, the level of estrogen in the blood drops slightly and
secretion of luteinizing hormone (LH) stimulates the
development of the corpus luteum. The corpus luteum now
begins to secrete increasing quantities of both estrogen and
progesterone. The progesterone prepares the endometrium
to receive a fertilized ovum by causing it to increase in size
and to secrete nutrients into the uterine cavity.
If fertilization and implantation do not occur, the rising
levels of progesterone and estrogen from the cor-pus
luteum inhibit luteinizing hormone-releasing hor-mone
(LHRH) from the hypothalamus and LH from the anterior
pituitary gland. As a result, the corpus luteum degenerates
and becomes the corpus albicans. This will initiate another
menstrual cycle.
If fertilization and implantation do occur, the corpus
luteum will be maintained for about 4 months. During this
time, it continues to secrete estrogen and progesterone. The
corpus luteum is maintained by human chorionic
gonadotropin, a hormone produced by the developing
placenta. Once the placenta is developed, it will secrete
estrogen to support pregnancy and progesterone to both
support pregnancy and to cause breast development for
milk production in the mammary glands.
The length of a menstrual cycle is variable. It can be as
long as 40 days or as short as 21 days. It normally occurs
once each month from menarche (menAR-kee),
which is the first menstrual cycle, to menopause (MEN-
oh-pawz), which is the last menstrual cycle. Even though a
woman may have a regular menustrual cycle, she may not
necessarily be ovulating or releasing an egg. This may lead
to problems with fertility and conception.The Functions of Estrogen
The ovaries actually produce several types of estrogens:
estradiol, which is the most abundant and is mainly
responsible for the effects of estrogen on the body, and
estrone and estriol. The ovaries become active during
puberty, producing ova and estrogens. The estrogens cause
the development of the secondary sex characteristics of a
female. In addition to enlargement of the uterine tubes,
uterus, vagina, and external genitalia of the female,
estrogens cause the development of the breasts and the
appearance of pubic hair and axillary hair under the arms.
Fat gets deposited under the skin, resulting in the soft look
of a female. In particular, more fat is deposited around the
hips and breasts. The pelvic bone widens and the onset of
the menstrual cycle begins.The Vagina
The vagina (vah-JEYE-nah) has a number of functions. It
serves as a passageway for the menstrual flow. It is the
receptacle for the penis during sexual intercourse, or
coitus (KOH-ih-tus). It also is the lower portion of the
birth canal. There is a recess called the fornix (FOR-niks),
which surrounds the vaginal attachment to the cervix (see
Figure 19-6). The dorsal recess is called the posterior fornix
and is slightly larger than the two lateral fornices and the
ventral fornix. The fornix can accommodate the placing of
a contraceptive diaphragm, which prevents sperm from
entering the uterus.