Female Reproductive System
All living things reproduce. Reproduction - the process by which
organisms make more organisms like themselves - is one of the
things that sets living things apart from nonliving matter. But
even though the reproductive system is essential to keeping a
species alive, unlike other body systems, it's not essential to
keeping an individual alive.
In the human reproductive process, 2 kinds of sex cells, or
gametes, are involved. The male gamete, or sperm, and the female
gamete, the egg or ovum, meet in the female's reproductive
system to create a new individual.
Both the male and female reproductive systems are essential for
reproduction. The female needs a male to fertilize her egg, even
though it is she who carries offspring through pregnancy and
childbirth.
Humans, like other organisms, pass certain characteristics of
themselves to the next generation through their genes, the special
carriers of human traits. The genes that parents pass along to
their children are what make children similar to others in their
family, but they are also what make each child unique. These genes
come from the male's sperm and the female's egg, which are
produced by the male and female reproductive systems.
About the Female Reproductive System
Most species have two sexes: male and female. Each sex has its
own unique reproductive system. They are different in shape and
structure, but both are specifically designed to produce, nourish,
and transport either the egg or sperm.
Unlike the male, the human female has a reproductive system
located entirely in the pelvis. The external part of the female
reproductive organs is called the vulva, which means covering.
Located between the legs, the vulva covers the opening to the
vagina and other reproductive organs located inside the body.
The fleshy area located just above the top of the vaginal
opening is called the mons pubis. Two pairs of skin flaps called
the labia (which means lips) surround the vaginal opening. The
clitoris, a small sensory organ, is located toward the front of the
vulva where the folds of the labia join. Between the labia are
openings to the urethra (the canal that carries urine from the
bladder to the outside of the body) and vagina. Once girls become
sexually mature, the outer labia and the mons pubis are covered by
pubic hair.
A female's internal reproductive organs are the vagina,
uterus, fallopian tubes, and ovaries.
The vagina is a muscular, hollow tube that extends from the
vaginal opening to the uterus. The vagina is about 3 to 5 inches (8
to 12 centimeters) long in a grown woman. Because it has muscular
walls, it can expand and contract. This ability to become wider or
narrower allows the vagina to accommodate something as slim as a
tampon and as wide as a baby. The vagina's muscular walls are
lined with mucous membranes, which keep it protected and moist.
The vagina serves three purposes:
- It's where the penis is inserted during sexual
intercourse.
- It's the pathway that a baby takes out of a woman's
body during childbirth, called the birth canal.
- It provides the route for the menstrual blood (the period) to
leave the body from the uterus.
A thin sheet of tissue with one or more holes in it called the
hymen partially covers the opening of the vagina. Hymens are often
different from female to female. Most women find their hymens have
stretched or torn after their first sexual experience, and the
hymen may bleed a little (this usually causes little, if any,
pain). Some women who have had sex don't have much of a change
in their hymens, though.
The vagina connects with the uterus, or womb, at the cervix
(which means neck). The cervix has strong, thick walls. The opening
of the cervix is very small (no wider than a straw), which is why a
tampon can never get lost inside a girl's body. During
childbirth, the cervix can expand to allow a baby to pass.
The uterus is shaped like an upside-down pear, with a thick
lining and muscular walls - in fact, the uterus contains some of
the strongest muscles in the female body. These muscles are able to
expand and contract to accommodate a growing fetus and then help
push the baby out during labor. When a woman isn't pregnant,
the uterus is only about 3 inches (7.5 centimeters) long and 2
inches (5 centimeters) wide.
At the upper corners of the uterus, the fallopian tubes connect
the uterus to the ovaries. The ovaries are two oval-shaped organs
that lie to the upper right and left of the uterus. They produce,
store, and release eggs into the fallopian tubes in the process
called ovulation. Each ovary measures about 11/2 to 2 inches (4 to
5 centimeters) in a grown woman.
There are two fallopian tubes, each attached to a side of the
uterus. The fallopian tubes are about 4 inches (10 centimeters)
long and about as wide as a piece of spaghetti. Within each tube is
a tiny passageway no wider than a sewing needle. At the other end
of each fallopian tube is a fringed area that looks like a funnel.
This fringed area wraps around the ovary but doesn't completely
attach to it. When an egg pops out of an ovary, it enters the
fallopian tube. Once the egg is in the fallopian tube, tiny hairs
in the tube's lining help push it down the narrow passageway
toward the uterus.
The ovaries are also part of the
endocrine system
because they produce female sex hormones such as estrogen and
progesterone.
What the Female Reproductive System Does
The female reproductive system enables a woman to:
- produce eggs (ova)
- have sexual intercourse
- protect and nourish the fertilized egg until it is fully
developed
- give birth
Sexual reproduction couldn't happen without the sexual
organs called the gonads. Although most people think of the gonads
as the male testicles, both sexes actually have gonads: In females
the gonads are the ovaries. The female gonads produce female
gametes (eggs); the male gonads produce male gametes (sperm). After
an egg is fertilized by the sperm, the fertilized egg is called the
zygote.
When a baby girl is born, her ovaries contain hundreds of
thousands of eggs, which remain inactive until puberty begins. At
puberty, the pituitary gland, located in the central part of the
brain, starts making hormones that stimulate the ovaries to produce
female sex hormones, including estrogen. The secretion of these
hormones causes a girl to develop into a sexually mature woman.
Toward the end of puberty, girls begin to release eggs as part
of a monthly period called the menstrual cycle. Approximately once
a month, during ovulation, an ovary sends a tiny egg into one of
the fallopian tubes.
Unless the egg is fertilized by a sperm while in the fallopian
tube, the egg dries up and leaves the body about 2 weeks later
through the uterus - this is menstruation. Blood and tissues from
the inner lining of the uterus combine to form the menstrual flow,
which in most girls lasts from 3 to 5 days. A girl's first
period is called menarche.
It's common for women and girls to experience some
discomfort in the days leading to their periods. Premenstrual
syndrome (PMS) includes both physical and emotional symptoms that
many girls and women get right before their periods, such as acne,
bloating, fatigue, backaches, sore breasts, headaches,
constipation, diarrhea, food cravings, depression, irritability, or
difficulty concentrating or handling stress. PMS is usually at its
worst during the 7 days before a girl's period starts and
disappears once it begins.
Many girls also experience abdominal cramps during the first few
days of their periods caused by prostaglandins, chemicals in the
body that make the smooth muscle in the uterus contract. These
involuntary contractions can be either dull or sharp and
intense.
It can take up to 2 years from menarche for a girl's body to
develop a regular menstrual cycle. During that time, her body is
adjusting to the hormones puberty brings. On average, the monthly
cycle for an adult woman is 28 days, but the range is from 23 to 35
days.
If a female and male have sex within several days of the
female's ovulation, fertilization can occur. When the male
ejaculates (when semen leaves a male's penis), between 0.05 and
0.2 fluid ounces (1.5 to 6.0 milliliters) of semen is deposited
into the vagina. Between 75 and 900 million sperm are in this small
amount of semen, and they "swim" up from the vagina
through the cervix and uterus to meet the egg in the fallopian
tube. It takes only one sperm to fertilize the egg.
About a week after the sperm fertilizes the egg, the fertilized
egg (zygote) has become a multicelled blastocyst. A blastocyst is
about the size of a pinhead, and it's a hollow ball of cells
with fluid inside. The blastocyst burrows itself into the lining of
the uterus, called the endometrium. The hormone estrogen causes the
endometrium to become thick and rich with blood. Progesterone,
another hormone released by the ovaries, keeps the endometrium
thick with blood so that the blastocyst can attach to the uterus
and absorb nutrients from it. This process is called
implantation.
As cells from the blastocyst take in nourishment, another stage
of development, the embryonic stage, begins. The inner cells form a
flattened circular shape called the embryonic disk, which will
develop into a baby. The outer cells become thin membranes that
form around the baby. The cells multiply thousands of times and
move to new positions to eventually become the embryo.
After approximately 8 weeks, the embryo is about the size of an
adult's thumb, but almost all of its parts - the brain and
nerves, the heart and blood, the stomach and intestines, and the
muscles and skin - have formed.
During the fetal stage, which lasts from 9 weeks after
fertilization to birth, development continues as cells multiply,
move, and change. The fetus floats in amniotic fluid inside the
amniotic sac. The fetus receives oxygen and nourishment from the
mother's blood via the placenta, a disk-like structure that
sticks to the inner lining of the uterus and connects to the fetus
via the umbilical cord. The amniotic fluid and membrane cushion the
fetus against bumps and jolts to the mother's body.
Pregnancy lasts an average of 280 days - about 9 months. When
the baby is ready for birth, its head presses on the cervix, which
begins to relax and widen to get ready for the baby to pass into
and through the vagina. The mucus that has formed a plug in the
cervix loosens, and with amniotic fluid, comes out through the
vagina when the mother's water breaks.
When the contractions of labor begin, the walls of the uterus
contract as they are stimulated by the pituitary hormone oxytocin.
The contractions cause the cervix to widen and begin to open. After
several hours of this widening, the cervix is dilated (opened)
enough for the baby to come through. The baby is pushed out of the
uterus, through the cervix, and along the birth canal. The
baby's head usually comes first; the umbilical cord comes out
with the baby and is cut after the baby is delivered.
The last stage of the birth process involves the delivery of the
placenta, which is now called the afterbirth. After it has
separated from the inner lining of the uterus, contractions of the
uterus push it out, along with its membranes and fluids.
Problems of the Female Reproductive System
Your daughter may sometimes experience reproductive system
problems. Below are some examples of disorders that affect the
female reproductive system.
Problems of the Vulva and Vagina
-
Vulvovaginitis
is an inflammation of the vulva and vagina. It may be caused by
irritating substances (such as laundry soaps or bubble baths).
Poor personal hygiene (such as wiping from back to front after a
bowel movement) may also cause this problem. Symptoms include
redness and itching in the vaginal and vulvar areas and sometimes
vaginal discharge. Vulvovaginitis can also be caused by an
overgrowth of
Candida
, a fungus normally present in the vagina.
-
Nonmenstrual vaginal bleeding
is most commonly due to the presence of a vaginal foreign body,
often wadded-up toilet paper. It may also be due to urethral
prolapse, a condition in which the mucous membranes of the
urethra protrude into the vagina and form a tiny, doughnut-shaped
mass of tissue that bleeds easily. It can also be due to a
straddle injury (such as when falling onto a beam or bicycle
frame) or vaginal trauma from sexual abuse.
-
Labial adhesions
, the sticking together or adherence of the labia in the midline,
usually appear in infants and young girls. Although there are
usually no symptoms associated with this condition, labial
adhesions can lead to an increased risk of urinary tract
infection. Sometimes topical estrogen cream is used to help
separate the labia.
Problems of the Ovaries and Fallopian Tubes
-
Ectopic pregnancy
occurs when a fertilized egg, or zygote, doesn't travel into
the uterus, but instead grows rapidly in the fallopian tube. A
woman with this condition can develop severe abdominal pain and
should see a doctor because surgery may be necessary.
-
Endometriosis
occurs when tissue normally found only in the uterus starts to
grow outside the uterus - in the ovaries, fallopian tubes, or
other parts of the pelvic cavity. It can cause abnormal bleeding,
painful periods, and general pelvic pain.
-
Ovarian tumors
, although they're rare, can occur. Girls with ovarian tumors
may have abdominal pain and masses that can be felt in the
abdomen. Surgery may be needed to remove the tumor.
-
Ovarian cysts
are noncancerous sacs filled with fluid or semisolid material.
Although they are common and generally harmless, they can become
a problem if they grow very large. Large cysts may push on
surrounding organs, causing abdominal pain. In most cases, cysts
will disappear on their own and treatment is unnecessary. If the
cysts are painful, a doctor may prescribe birth control pills to
alter their growth, or they may be removed by a surgeon.
-
Polycystic ovary syndrome
is a hormone disorder in which too many male hormones (androgens)
are produced by the ovaries. This condition causes the ovaries to
become enlarged and develop many fluid-filled sacs, or cysts. It
often first appears during the teen years. Depending on the type
and severity of the condition, it may be treated with drugs to
regulate hormone balance and menstruation.
-
Ovarian torsion
, or the twisting of the ovary, can occur when an ovary becomes
twisted because of a disease or a developmental abnormality. The
torsion blocks blood from flowing through the blood vessels that
supply and nourish the ovaries. The most common symptom is lower
abdominal pain. Surgery is usually necessary to correct it.
Menstrual Problems
A variety of
menstrual problems
can affect girls, including:
-
Dysmenorrhea
is when a girl has painful periods.
-
Menorrhagia
is when a girl has a very heavy periods with excess
bleeding.
-
Oligomenorrhea
is when a girl misses or has infrequent periods, even though
she's been menstruating for a while and isn't
pregnant.
-
Amenorrhea
is when a girl has not started her period by the time she is 16
years old or 3 years after starting puberty, has not developed
signs of puberty by age 14, or has had normal periods but has
stopped menstruating for some reason other than pregnancy.
Infections of the Female Reproductive System
-
Sexually transmitted diseases (STDs)
.
These include infections and diseases such as pelvic inflammatory
disease (PID), human immunodeficiency virus/acquired
immunodeficiency syndrome (HIV/AIDS), human papillomavirus (HPV,
or genital warts), syphilis, chlamydia, gonorrhea, and genital
herpes. Most are spread from one person to another by sexual
contact.
-
Toxic shock syndrome
.
This uncommon illness is caused by toxins released into the body
during a type of bacterial infection that is more likely to
develop if a tampon is left in too long. It can produce high
fever, diarrhea, vomiting, and shock.
If you think your daughter may have symptoms of a problem with
her reproductive system or if you have questions about her growth
and development, talk to your doctor - many problems with the
female reproductive system can be treated.
Reviewed by:
Steven Dowshen, MD
Date reviewed: July 2007
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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