The Reproductive System

What Does The Reproductive System Do?

Life is sexually transmitted. Through the reproductive system.

The reproductive system is a collection of organs that work together to produce a new human life.

Sperm from the male fertilizes the female’s egg, or ovum, in the fallopian tube. The fertilized egg travels from the fallopian tube to the uterus, where the fetus develops over a period of nine months.

What Makes Up The Reproductive System?

Male Reproductive System

There are external and internal components of the male reproductive system.

Male Reproductive System

External Reproductive Structures


    The penis is the male organ for sexual intercourse. It has three parts: the root, which attaches to the wall of the abdomen; the body, or shaft; and the glans, which is the cone-shaped end of the penis. The glans, which also is called the head of the penis, is covered with a loose layer of skin called foreskin. (This skin is sometimes removed in a procedure called circumcision.) The opening of the urethra, the tube that transports semen and urine, is at the tip of the glans penis. The penis also contains a number of sensitive nerve endings.

    The body of the penis is cylindrical in shape and consists of three internal chambers. These chambers are made up of special, sponge-like erectile tissue. This tissue contains thousands of large spaces that fill with blood when the man is sexually aroused. As the penis fills with blood, it becomes rigid and erect, which allows for penetration during sexual intercourse. The skin of the penis is loose and elastic to accommodate changes in penis size during an erection.

    Semen, which contains sperm, is expelled (ejaculated) through the end of the penis when the man reaches sexual climax (orgasm). When the penis is erect, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm.

    5 Interesting Facts About The Reproductive System

    1. At birth, a woman has between 1 and 2 million potential eggs. By the time she reaches puberty, she has 300,000 to 400,000. However, she only releases about 300 to 400 during her child-bearing years.

    2. About 500 million sperm mature every day in a healthy male.

    3. The average lifespan of an egg once it is released from the ovary is 12-24 hours.

    4. The average life span of a sperm is 2-3 days.

    5. The female human body is capable of giving birth to 35 children in one lifetime.


    The scrotum is the loose pouch-like sac of skin that hangs behind the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The scrotum has a protective function and acts as a climate control system for the testes. For normal sperm development, the testes must be at a temperature slightly cooler than the body temperature. Special muscles in the wall of the scrotum allow it to contract and relax, moving the testicles closer to the body for warmth and protection or farther away from the body to cool the temperature.

    Testicles (testes)

    The testes are oval organs about the size of large olives that lie in the scrotum, secured at either end by a structure called the spermatic cord. Most men have two testes. The testes are responsible for making testosterone, the primary male sex hormone, and for generating sperm. Within the testes are coiled masses of tubes called seminiferous tubules. These tubules are responsible for producing the sperm cells through a process called spermatogenesis.


    The epididymis is a long, coiled tube that rests on the backside of each testicle. It functions in the transport and storage of the sperm cells that are produced in the testes. It also is the job of the epididymis to bring the sperm to maturity, since the sperm that emerge from the testes are immature and incapable of fertilization. During sexual arousal, contractions force the sperm into the vas deferens.

Internal Reproductive Organs

    Vas deferens

    The vas deferens is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. The vas deferens transports mature sperm to the urethra in preparation for ejaculation.

    Ejaculatory ducts

    These are formed by the fusion of the vas deferens and the seminal vesicles. The ejaculatory ducts empty into the urethra.


    The urethra is the tube that carries urine from the bladder to outside of the body. In males, it has the additional function of expelling (ejaculating) semen when the man reaches orgasm. When the penis is erect during sex, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm.

    Seminal vesicles

    The seminal vesicles are sac-like pouches that attach to the vas deferens near the base of the bladder. The seminal vesicles produce a sugar-rich fluid (fructose) that provides sperm with a source of energy and helps with the sperms’ motility (ability to move). The fluid of the seminal vesicles makes up most of the volume of a man’s ejaculatory fluid, or ejaculate.

    Prostate gland

    The prostate gland is a walnut-sized structure that is located below the urinary bladder in front of the rectum. The prostate gland contributes additional fluid to the ejaculate. Prostate fluids also help to nourish the sperm. The urethra, which carries the ejaculate to be expelled during orgasm, runs through the center of the prostate gland.

    Bulbourethral glands

    The bulbourethral glands, or Cowper’s glands, are pea-sized structures located on the sides of the urethra just below the prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra. This fluid serves to lubricate the urethra and to neutralize any acidity that may be present due to residual drops of urine in the urethra.

Female Reproductive System

The female reproductive anatomy includes both external and internal structures.

Female Reproductive System

External Reproductive Structures

    Labia majora

    The labia majora (“large lips”) enclose and protect the other external reproductive organs. During puberty, hair growth occurs and the skin of the labia majora, which also contain sweat and oil-secreting glands.

    Labia minora

    The labia minora (“small lips”) can have a variety of sizes and shapes. They lie just inside the labia majora, and surround the openings to the vagina (the canal that joins the lower part of the uterus to the outside of the body) and urethra (the tube that carries urine from the bladder to the outside of the body).

    Bartholin’s glands

    These glands are located next to the vaginal opening on each side and produce a fluid (mucus) secretion.


    The two labia minora meet at the clitoris, a small, sensitive protrusion that is comparable to the penis in males. The clitoris is covered by a fold of skin, called the prepuce, which is similar to the foreskin at the end of the penis. Like the penis, the clitoris is very sensitive to stimulation and can become erect.

Internal Reproductive Organs


    The vagina is a canal that joins the cervix (the lower part of uterus) to the outside of the body. It also is known as the birth canal. The vagina is about 3 to 5 inches (8 to 12 centimeters) long in a grown woman

    Uterus (womb)

    The uterus is a hollow, pear-shaped organ that is the home to a developing fetus. The uterus is divided into two parts: the cervix, which is the lower part that opens into the vagina, and the main body of the uterus, called the corpus. The corpus can easily expand to hold a developing baby. A canal through the cervix allows sperm to enter and menstrual blood to exit. 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. The lining of the uterus is called the endometrium, and has a rich capillary supply to bring food to any embryo that might implant there.


    The ovaries are small, oval-shaped glands that are located on either side of the uterus. The ovaries produce eggs and hormones. The ovaries are also part of the endocrine system because they produce female sex hormones such as estrogen and progesterone

    Fallopian tubes

    These are narrow tubes that are attached to the upper part of the uterus and serve as pathways for the ova (egg cells) to travel from the ovaries to the uterus. Fertilization of an egg by a sperm normally occurs in the fallopian tubes. The fertilized egg then moves to the uterus, where it implants to the uterine lining. The fallopian tubes are about 4 inches (10 centimeters) long and about as wide as a piece of spaghetti.

How Does The Reproductive System Work?

The ovaries release one “egg” (or ovum) each month. The egg travels along the Fallopian tubes toward the uterus. As this is happening, the endometrium, or lining of the uterus, becomes thick with fluid and blood (to prepare a suitable home for a growing baby).

If a female has sexual intercourse with a male during this time, pregnancy is possible.

At the peak of sexual intercourse, the male ejaculates, releasing millions of sperm through the woman’s vagina toward the uterus. Some of the sperm reach the uterus and then the fallopian tube, where one meets the egg, fertilizing (or joining) it.

This fertilized egg then attaches to the wall of the uterus. (If the egg is not fertilized, the egg as well as the thick lining that has recently developed will shed themselves through the vagina.)

The human fetus requires about nine months within the uterus to prepare itself for birth. During this time, the baby is nourished by whatever the mother brings into her body, reaching the fetus via a tube called the umbilical cord.

When the baby is ready for birth, the muscles of the uterus begin contracting (tightening and loosening) in preparation for the actual pushing out of the baby. During labor, the muscles of the vagina, formerly a narrow tube, widen enough to allow the passage of the baby. With the delivery of the child, the reproductive system has completed the process of reproduction.

What Can Go Wrong With Your Reproductive System?

Male Reproductive Problems

Disorders of the Scrotum, Testicles, or Epididymis

    Testicular injury

    Even a mild injury to the testicles can cause severe pain, bruising, or swelling. Most testicular injuries occur when the testicles are struck, hit, kicked, or crushed, usually during sports or due to other trauma. Testicular torsion is when one of the testicles twists around, cutting off its blood supply.


    This is a varicose vein (an abnormally swollen vein) in the network of veins that run from the testicles. Varicoceles commonly develop while a guy is going through puberty. A varicocele is usually not harmful, although in some people it may damage the testicle or decrease sperm production.

    Testicular cancer

    This is one of the most common cancers in men younger than 40. It occurs when cells in the testicle divide abnormally and form a tumor. Testicular cancer can spread to other parts of the body, but if it’s detected early, the cure rate is excellent.


    Inflammation of the epididymis, the coiled tubes that connect the testes with the vas deferens. It is usually caused by an infection, such as the sexually transmitted disease chlamydia, and results in pain and swelling next to one of the testicles.


    A hydrocele occurs when fluid collects in the membranes surrounding the testes. Hydroceles may cause swelling in the scrotum around the testicle but are generally painless. In some cases, surgery may be needed to correct the condition.

    Inguinal hernia

    When a portion of the intestines pushes through an abnormal opening or weakening of the abdominal wall and into the groin or scrotum, it is known as an inguinal hernia. The hernia may look like a bulge or swelling in the groin area. It can be corrected with surgery.

Disorders of the Penis

    Inflammation of the penis

    Symptoms of penile inflammation include redness, itching, swelling, and pain. Balanitis occurs when the glans (the head of the penis) becomes inflamed. Posthitis is foreskin inflammation, which is usually due to a yeast or bacterial infection.


    A disorder in which the urethra opens on the underside of the penis, not at the tip.


    When the testicles do not produce enough testosterone.

Female Reproductive Problems

Disorders of the Vagina


    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

    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, donut-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.

Disorders of the Ovaries and Fallopian Tubes

    Ectopic Pregnancy

    When a fertilized egg, or zygote, doesn’t travel into the uterus, but instead grows rapidly in the fallopian tube.


    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 rare, they can occur. Women 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

    Noncancerous sacs filled with fluid or semi-solid 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

    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.

Menstrual Problems


    When a woman has painful periods.


    When a woman has a very heavy periods with excess bleeding.


    When a woman misses or has infrequent periods, even though she’s been menstruating for a while and isn’t pregnant.


    When a woman hasn’t 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 infections.

    These include infections and diseases such as pelvic inflammatory disease (PID), human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), human papilloma virus (HPV, or genital warts), syphilis, chlamydia, gonorrhea, and genital herpes. Most are spread from one person to another by sexual intercourse.

    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.

How Do Your Keep Your Reproductive System Healthy?

To keep your reproductive system healthy, follow these tips . . .

  1. Practice safe sex. Some sexually transmitted diseases (STDs) can render you infertile. Many of these diseases have no symptoms at first, so you can severely damage your fertility before you know you have them.

  2. Exercise it. Some studies suggest that a few male ejaculations per week will help keep the reproductive system healthy.

  3. Lead a healthy lifestyle. A nutritious, balanced diet, as well as regular physical activity will not only keep you fit; it will also ensure that your reproductive system is in good shape and functioning at peak efficiency.

This article is part of a series called “Your Body: An Owner’s Manual” which explains how your body systems work and how to maintain them. The first article in the series included a picture of my wife, fitness coach Kathie Lamir, who exemplifies a healthy body. Pictures of Kathie were so well received that I have included one with each article in the series

Fitness Coach Kathie Lamir

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