By: Ryan Burke . The Female Reproductive System. The Female Reproduction System.
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The female reproductive system is designed to carry out several functions. It produces the female egg cells necessary for reproduction, called the ova or oocytes. The system is designed to transport the ova to the site of fertilization. Conception, the fertilization of an egg by a sperm, normally occurs in the fallopian tubes. The next step for the fertilized egg is to implant into the walls of the uterus, beginning the initial stages of pregnancy. If fertilization and/or implantation does not take place, the system is designed to menstruate (the monthly shedding of the uterine lining). In addition, the female reproductive system produces female sex hormones that maintain the reproductive cycle.
The lower one-third of the uterus is the tubular "cervix," which extends downward into the upper portion of the vagina. The cervix surrounds the opening called the "cervical orifice," through which the uterus communicates with the vagina.
The fallopian tube extends from the uterus to the ovary. This tube carries eggs and sperm and is where fertilization of the egg, or "ovum" takes place. The fallopian tubes lie in the pelvic portion of the abdominal cavity and each tube reaches from an ovary to become the upper part of the uterus. This funnel-shaped tube is about three inches in length. The larger end of the funnel is divided into feathery, finger-like projections which lie close to the ovary. These beating projections, along with muscle contractions, force the ovum down the funnel's small end, which opens into the uterus.
After sexual intercourse, sperm swim up this funnel from the uterus. The lining of the tube and its secretions sustain both the egg and the sperm, encouraging fertilization and nourishing the egg until it reaches the uterus. If an egg splits in two after fertilization, identical or "maternal" twins are produced. If separate eggs are fertilized by different sperm, the mother gives birth to un-identical or "fraternal" twins.
The labia (singular, labium) minor are flattened lengthwise into folds located with the cleft between the labia major. These folds extend along either side of the vestibule. They are composed of connective tissue that is richly supplied with blood vessels, causing a pinkish appearance. In the back, near the anus, the labia minor merge with the labia major, while in the front they converge to form a hood-like covering around the clitoris.
The labia majora enclose and protect the other external reproductive organs. Literally translated as "large lips," the labia majora are relatively large and fleshy, and are comparable to the scrotum in males. The labia majora contain sweat and oil-secreting glands. After puberty, the labia majora are covered with hair.
The ovaries are a pair of oval or almond-shaped glands which lie on either side of the uterus and just below the opening to the fallopian tubes. In addition to producing eggs or "ova," the ovaries produce female sex hormones called estrogen and progesterone. The ovaries produce a female hormone, called estrogen, and store female sex cells or "ova." The female, unlike the male, does not manufacture the sex cells.
A girl baby is born with about 60,000 of these cells, which are contained in sac-like depressions in the ovaries. Each of these cells may have the potential to mature for fertilization, but in actuality, only about 400 ripen during the woman's lifetime.
The uterus or "womb" is a hollow, muscular organ in which a fertilized egg, called the "zygote," becomes embedded and in which the egg is nourished and allowed to develop until birth. It lies in the pelvic cavity behind the bladder and in front of the bowel. The uterus usually tilts forward at a ninety degree angle to the vagina, although in about 20% of women, it tilts backwards.
The uterus is lined with tissues which change during the menstrual cycle. These tissues build under the influence of hormones from the ovary. When the hormones withdraw after the menstrual cycle, the blood supply is cut off and the tissues and unfertilized egg are shed as waste.
During pregnancy, the uterus stretches from three to four inches in length to a size which will accommodate a growing baby. During this time, muscular walls increase from two to three ounces to about two pounds and these powerful muscles release the baby through the birth canal with great force. The womb shrinks back to half its pregnant weight before a baby is a week old. By the time the baby is a month old, the uterus may be as small as when the egg first entered.
The vagina is a muscular passage which forms a part of the female sex organs and which connects the neck of the uterus (called the "cervix") with the external genitals. The vagina, which is approximately two and one-half to four inches long, has muscular walls which are supplied with numerous blood vessels. These walls become erect when a woman is aroused as extra blood is pumped into these vessels.
The vagina has three functions: as a receptacle for the penis during sexual intercourse; as a outlet for blood during menstruation; and as a passageway for the baby to pass through at birth.
Females of reproductive age experience cycles of hormonal activity that repeat at about one-month intervals. With every cycle, a woman's body prepares for a potential pregnancy, whether or not that is the woman's intention. The term menstruation refers to the periodic shedding of the uterine lining.
The average menstrual cycle takes about 28 days and occurs in phases: the follicular phase, the ovulatory phase (ovulation), and the luteal phase.
There are four major hormones (chemicals that stimulate or regulate the activity of cells or organs) involved in the menstrual cycle: follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone.
This phase starts on the first day of your period. During the follicular phase of the menstrual cycle, the following events occur:
Two hormones, follicle stimulating hormone (FSH) and luteinizing hormone (LH) are released from the brain and travel in the blood to the ovaries.
The hormones stimulate the growth of about 15-20 eggs in the ovaries each in its own "shell," called a follicle.
These hormones (FSH and LH) also trigger an increase in the production of the female hormone estrogen.
As estrogen levels rise, like a switch, it turns off the production of follicle-stimulating hormone. This careful balance of hormones allows the body to limit the number of follicles that complete maturation, or growth.
As the follicular phase progresses, one follicle in one ovary becomes dominant and continues to mature. This dominant follicle suppresses all of the other follicles in the group. As a result, they stop growing and die. The dominant follicle continues to produce estrogen.
The ovulatory phase, or ovulation, starts about 14 days after the follicular phase started. The ovulatory phase is the midpoint of the menstrual cycle, with the next menstrual period starting about two weeks later. During this phase, the following events occur:
The rise in estrogen from the dominant follicle triggers a surge in the amount of luteinizing hormone that is produced by the brain.
This causes the dominant follicle to release its egg from the ovary.
As the egg is released (a process called ovulation) it is captured by finger-like projections on the end of the fallopian tubes (fimbriae). The fimbriae sweep the egg into the tube.
Also during this phase, there is an increase in the amount and a change in the consistency of mucus produced by the cervix (lower part of the uterus.) If a woman were to have intercourse during this time, this receptive mucus captures the man's sperm, nourishes it, and helps it to move towards the egg for fertilization.
The luteal phase begins right after ovulation and involves the following processes:
Once it releases its egg, the empty follicle develops into a new structure called the corpus luteum.
The corpus luteum secretes the hormone progesterone. Progesterone prepares the uterus for a fertilized egg to implant.
If intercourse has taken place and a man's sperm has fertilized the egg (a process called conception), the fertilized egg (embryo) will travel through the fallopian tube to implant in the uterus. The woman is now considered pregnant.
If the egg is not fertilized, it passes through the uterus. Not needed to support a pregnancy, the lining of the uterus breaks down and sheds, and the next menstrual period begins.
The vast majority of the eggs within the ovaries steadily die, until they are depleted at menopause. At birth, there are approximately 1 million eggs; and by the time of puberty, only about 300,000 remain. Of these, 300 to 400 will be ovulated during a woman's reproductive lifetime. The eggs continue to degenerate during pregnancy, with the use of birth control pills, and in the presence or absence of regular menstrual cycles.
Menopause is a normal condition that all women experience as they age. The term "menopause" is commonly used to describe any of the changes a woman experiences either just before or after she stops menstruating, marking the end of her reproductive period.
A woman is born with a finite number of eggs, which are stored in the ovaries. The ovaries also produce the hormones estrogen and progesterone, which regulate menstruation and ovulation. Menopause occurs when the ovaries no longer produce an egg every month and menstruation stops.
Menopause, when it occurs after the age of 40, is considered "natural" and is a normal part of aging. But, some women can experience menopause early, either as a result of surgery, such as hysterectomy, or damage to the ovaries, such as from chemotherapy. Menopause that occurs before the age of 40, regardless of the cause, is called premature menopause.
Most women approaching menopause or who are postmenopausal will experience hot flashes, a sudden feeling of warmth that spreads over the upper body that is often accompanied by blushing and some sweating. The severity of hot flashes varies from mild in most women to severe in others.Other common symptoms experienced around the time of menopause include:
Pregnancy has an average 40-week length. The first week is your period, and the very end of the second week marks the release of the egg—ovulation. The egg is fertilized early in the third week and typically implants in the uterus 6-12 days after ovulation. This means that using this dating method, you actually get pregnant during the third week. You can calculate your due date by adding seven days and subtracting three months from the first day of your last period.
Uterine lining development. At this point in your cycle, your uterine lining is developing under the influence of hormone your body secretes to make it receptive to the fertilized egg.
Your baby now weighs between 1 and 2 ounces and is about 3.6 inches long. This week your baby begins to develop hair. Soft, peachfuzz-like hair begins to appear on her head, although by delivery day its texture and color may change. Lanugo (very fine, downy hair) continues to grow over your baby's body to protect her delicate skin. Fine, soft eyebrows are also appearing.
Breathing motions. You won't be able to feel it, but your baby is practicing breathing motions, moving the amniotic fluid in and out of her lungs.
Prostate gland begins to develop in boys.
Ovaries descend from the abdomen into the pelvis in girls.
Growth hormone production. As the thyroid matures it produces more growth hormones.
Ears and eyes. They continue to move into place.
Neck elongation. Your baby's neck is getting longer.
Hand function. Tiny hands are beginning to function, although their movements may be mostly reflexive.
This week marks the beginning of the third trimester. And although your baby may not have grown much taller, she now weighs more than 2 pounds. Right now your baby looks like she will at birth, just a little thinner and smaller.
A big developmental change occurs as your baby's fused eyelids finally open. The lids have been closed since early pregnancy to protect the developing retina at the back of the eye. The retina is the part of the eye that receives light information and transmits the information to the brain for interpretation. The retina develops its normal layers during this week.
Organs and systems. Lungs, liver, and immune system are still developing.
Hearing. As hearing continues to develop, some scientists suggest your baby may start to recognize your voice, although sounds may be muffled because a waxy coating still covers the ears.
Response to sound. This will become more pronounced as the development of the auditory nerve is completed.
Brain. Her brain continues to grow and develop rapidly.
Your baby has probably reached 3 pounds and about 14 inches in length. She’s also filling out a bit as she continues to gain weight, and these layers of fat help her to appear less wrinkled.
As practice for breathing after birth, your baby mimics breathing movements by repeatedly moving her diaphragm in a rhythmic way. This can trigger hiccups if she inadvertently inhales amniotic fluid. A pint and a half of amniotic fluid now surrounds your baby, but that volume decreases as she gets bigger and has less room in your uterus.
Here's what else is happening this week:
Head. Your baby’s head continues to grow, and brain growth speeds up even more.
Hearing. It’s improving; nearly all babies can react by movement to sound by this week.
Now baby weighs almost 6.5 pounds and her total length is about 21 inches long. But she hasn't stopped growing yet; she'll continue to develop about a half ounce of fat a day. Still, overall growth does slow from here on out. That's fortunate since there is very little available space left in the womb.
Here are a few final developments taking place in week 37:
Immune system. It continues to strengthen and will continue to get stronger after birth yet will not be completely functional until early adulthood.
Dexterity. Your baby can now grasp with her fingers as dexterity improves.
Symptoms such as vaginal itching, burning, pain and discharge are some of the most common reasons that women seek medical care. Often, the problem is vaginitis, an inflammation of the vagina. In women of childbearing age, the most common cause is a bacterial infection. The main symptom is a smelly vaginal discharge, but some women have no symptoms. The treatment is antibiotics.
Other infections that can cause vaginitis include trichomoniasis and yeast infections. Some other causes of vaginal symptoms, including vaginal bleeding, are sexually transmitted diseases, vaginal cancer and vulvar cancer.
Sexually transmitted diseases (STDs) are infections that you can get from having sex with someone who has the infection. The causes of STDs are bacteria, parasites and viruses. There are more than 20 types of STDs, including:
Most STDs affect both men and women, but in many cases the health problems they cause can be more severe for women. If a pregnant woman has an STD, it can cause serious health problems for the baby.
Infertility is a term doctors use if a woman hasn't been able to get pregnant after at least one year of trying. If a woman keeps having miscarriages, it is also called infertility. Female infertility can result from physical problems, hormone problems, and lifestyle or environmental factors.
Most cases of infertility in women result from problems with producing eggs. One problem is premature ovarian failure, in which the ovaries stop functioning before natural menopause. In another, polycystic ovary syndrome (PCOS), the ovaries may not release an egg regularly or may not release a healthy egg.
About a third of the time, infertility is because of a problem with the woman. One third of the time, it is a problem with the man. Sometimes no cause can be found.