Key Concepts:
Vocabulary: sperm, testosterone, testes, scrotum, penis, semen, sterility
The Male Reproductive System
How Male Reproduction Works
Main Idea: The male reproductive system includes both external and internal organs that, with the help of hormones, allow physically mature males to produce children.
The two main functions of the male reproductive system are to produce and store sperm-the male gametes, or reproductive cells-and transfer them to the female’s body du ing sexual intercourse. During the early teen years, usually between the ages of 12 and 15, the male reproductive system reaches maturity. At that time, hormones produced in the pituitary gland stimulate the production of testosterone, the male sex hormone. Testosterone initiates physical changes that signal maturity, including broadening of the shoulders, development of muscles and facial and other body hair, and deepening of the voice. Testosterone also controls the production ofsperm. After puberty begins, a physically mature male is capable of producing sperm for the rest of his life.
External Reproductive Organs
A male’s external reproductive organs include the testes the penis, and the scrotum. The testes, also called testicles:are two small glands that secrete testosterone and produce sperm. They are located in the scrotum, an external skin sac. The penis is a tube-shaped organ that extends from the trunk of the body just above the testes. The penis is composed of spongy tissue that contains many blood vessels. When blood flow to the penis increases, it becomes enlarged and erect, causing an erection. Erections are normal body functions that occur more easily and more frequently during puberty. They can occur for no reason.
When the penis becomes erect, semen can be ejected from the body. Semen is a thick fluid containing sperm and other secretions from the male reproductive system. At the height of sexual arousal, a series of muscular contractions knownas ejaculation may occur. Fertilization-the joining of a male sperm cell and a female egg cell-can result if ejaculation occurs during sexual intercourse.
At birth, the tip of the penis is covered by a thin, loose skin, called the foreskin. Some parents choose circumcision, surgical removal of the foreskin of the penis, for their male children. In general, circumcision is often chosen for cultural or religious reasons. Sperm cannot live in temperatures higher than the normal body temperature of 98.6 degrees F.
The scrotum protects sperm by keeping the testes slightly below the normal body temperature. When body temperature rises muscles attached to the scrotum relax, causing the testes to lower away from the body. If body temperature lowers, the muscles tighten, moving the testes closer to the body for warmth. Tight clothing that holds the testes too close to the body may interfere with sperm production.
When a male begins to produce sperm, he may experience nocturnal emissions, an ejaculation that occurs when sperm are released during sleep.This is a normal occurrence to relieve the buildup of pressure as sperm begin to produce during puberty.
Internal Reproductive Organs
Although sperm are produced in the testes, which are suspended outside the body, they must travel through several structures inside the body before they are released. These structures include the vas deferens, the urethra, the seminal vesicles, and the prostate and Cowper’s glands. Figure 16.5 shows the path taken by sperm cells from the testes until they are released from the body.
Maintaining Reproductive Health
Main Idea: Male reproductive health involves care and monitoring throughout a male’s lifetime.
As with any other body system, the male reproductive system needs care. Ways of caring for the male reproductive system include practicing good personal hygiene, using adequate protection, practicing self-examination, and getting regular medical checkups.
Bathe regularly. Males should shower or bathe daily, thoroughly cleansing the penis and scrotum. Uncircumcised males should take care to wash under the foreskin.
Wear protective equipment. Use a protective cup or athletic supporter during physical activities to shield the external reproductive organs.
Male Reproductive System Problems
The organs of the male reproductive system can be affected by both functional and structural problems.
Some problems of the male reproductive system are described below. Males should watch for the signs ofthese problems, as well as signs of infections from STDs.
Inguinal hernia. An inguinal hernia occurs when part of the intestines push through a tear in the abdominal wall. The tear may be caused by straining the abdominal muscles or lifting heavy objects. Symptoms include a lump in the groin near the thigh, pain in the groin, or blockage of the intestine. Surgery can repair an inguinal hernia.
Sterility is the inability to reproduce, as a result of too few sperm or sperm of poor quality. Exposure to X-rays or other radiation, toxic chemicals, and lead, can cause sterility. Other causes include hormonal imbalances, mumps contracted during adulthood, or using certain medications or drugs such as anabolic steroids. STDs can also cause sterility.
Testicular cancer. Testicular cancer can affect males of any age, but occurs most often in males between the ages of 14 and 40. With early detection, most testicular cancer is treatable through surgery, radiation, or chemotherapy.
Prostate problems and prostate cancer. The prostate gland can become enlarged as a result of an infection, a tumor, or age. Early detection of prostate cancer increases survival rates.
How to Do a Testicular Self-Exam (TSE)
The American Cancer Society recommends that males perform a self-exam for testicular cancer once a month.
Standing in front of a mirror, look for swelling. Examine each testicle with both hands. Roll the testicle gently between the thumbs and forefingers.
Cancerous lumps usually are found on the side of the testicle but can appear on the front. Find the epididymis, the soft tubelike structure behind each testicle, so that you won’t mistake it for a lump.
Most lumps are not cancerous. If you do find a lump or experience pain or swelling, however, consult a health care professional.
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