What jobs do the external sex organs do?
The external male sex organs include the penis and the scrotum. The main purpose of the external sex organs is to allow for sexual intercourse and sexual pleasure. The structure of the penis is similar to that of the female clitoris, apart from the fact that the clitoris is mostly inside the body. During the time in the womb, they both develop from the same organ.
The penis can carry and release the man’s sperm into a woman's vagina. The round glans (head) of the penis is located at the tip of the longer shaft of the penis. It is covered with a mucous membrane. The movable foreskin (partially) covers the head of the penis. In some men, the foreskin has been shortened or removed in a medical procedure known as circumcision.
A tube called the urethra runs through the inside of the penis. Urine leaves the body through the urethra, and so does semen (the fluid that carries sperm) during ejaculation. The shaft and the head of the penis contain erectile tissues called corpora cavernosa. These tissues are like sponges. During sexual arousal, blood builds up in the corpora cavernosa until they are full and firm. This allows the penis to become erect and stiff (erection). In most men, it also becomes longer and thicker.
The scrotum is a bag of skin that surrounds the testicles, the epididymis and the start of the vas deferens.
The head of the penis and the skin on the penis, scrotum and the surrounding area contain a dense network of nerve fibers. This makes the external sex organs very sensitive. As a result, touching and rubbing this area can cause sexual arousal and increased pleasure that may lead to orgasm and trigger ejaculation.
What jobs do the internal sex organs do?
The main internal male sex organs include:
- Vas deferens tubes
- Seminal vesicles
The two round or egg-shaped testicles are the male reproductive glands (gonads): This is where the sperm cells are produced. Only these cells are capable of fertilizing a female egg cell. The testicles also produce the male sex hormone testosterone. They start to develop inside the abdominal cavity of a male embryo. As the embryo grows, they drop down out of the abdominal cavity and into the scrotum through the inguinal canals.
A worm-shaped epididymis is attached to each testicle. The epididymis takes the sperm cells from the testicles and allows them to mature into sperm that can move. The mature sperm are stored in the epididymis until the next ejaculation.
Both of the thin vas deferens tubes lead from the epididymis to the prostate. There they join the urethra tube, through which sperm can leave the body.
Just before the vas deferens tubes reach the urethra, they pass by the seminal vesicles. The seminal vesicles produce a fluid that mixes with the sperm cells to form semen. One part of the semen is produced by smaller glands near the base of the urethra and in the prostate. During ejaculation, the muscles in the pelvic floor contract. This causes the semen to be squirted out of the urethra. The released semen is called ejaculate (or "come").
What possible problems can occur?
Various problems may occur if the male sex organs change or are affected by medical conditions:
- Pain, for example constant or only during sex
- Itching, red skin and swelling
- Discharge from the urethra
- Burning sensation and difficulties urinating (peeing), urinary retention
- Erection problems and fertility problems
- Painful, long-lasting erection (priapism)
- Hormonal imbalances
Some men experience problems related to other underlying conditions – such as erection problems in men who have diabetes. Other men have problems because changes occur in only a single organ, such as a benign enlarged prostate.
In general, problems in the genital area can be caused by many different things, such as viral, bacterial or fungal infections. Typical examples include genital warts, inflammation of the head of the penis (balanitis) or inflammations caused by sexually transmitted infections like gonorrhea.
As a result of developmental disorders or malformations, the testicles may not drop down from the abdominal cavity into the scrotum before birth. This can cause infertility. If the foreskin – which is still attached to the head of the penis in young boys – does not loosen during the first few years of the boy’s life, he will have a tight foreskin (phimosis). In some men, the connective tissue in the penis becomes hardened and tight, causing the penis to curve.
Problems are often associated with the blood vessels, too. Varicose veins on the testicles (varicoceles) can cause swelling, pain and infertility, for instance. One testicle can become painfully twisted and then no longer get a proper supply of blood. If that happens, some testicle tissue may die off. Erection problems are often caused by chronically damaged blood vessels in the penis.
If an erect penis is suddenly bent sharply or squashed, the blood-filled erectile tissue may become damaged. This can cause major bruising (“penile fracture”).
Non-cancerous growths may occur in tissue like the skin or the connective tissue of the penis or scrotum. They may also develop in the gland tissue of the internal male sex organs, like the testicles or the epididymis. The most common cancerous tumors that affect the male sex organs include prostate cancer, testicular cancer and skin cancer on the penis. Tumors on the penis often develop due to abnormal changes in skin cells or mucous membrane cells. Known as dysplasia, these changes make the cells multiply faster than normal. Dyplasia on the penis is also called penile intraepithelial neoplasia (PIN).
Brandes R, Lang F, Schmidt R. Physiologie des Menschen: mit Pathophysiologie. Berlin: Springer; 2019.
Lippert H. Lehrbuch Anatomie. München: Urban und Fischer; 2017.
Menche N. Biologie Anatomie Physiologie. München: Urban und Fischer; 2016.
Pschyrembel Online. 2021.
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