The penis is one of the external structures of the male reproductive system.
The penis has three parts: the root, which attaches to the wall of the abdomen;
the body, or shaft; and the glans penis, which is the cone-shaped end (head).
The opening of the urethra, the tube that transports semen and urine, is at the
tip of the glans penis.
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 caverns 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 (the male reproductive cells), is expelled
through the end of the penis when the man reaches sexual climax (orgasm).
Disorders of the penis can affect a man’s sexual functioning and fertility.
What disorders affect the penis?
Some disorders that affect the penis include the following:
Priapism
Priapism is a persistent, often painful erection that can last from several
hours to a few days. The priapism erection is not associated with sexual
activity and is not relieved by orgasm. It occurs when blood flows into the
penis but is not adequately drained. Common causes of priapism include:
- Alcohol or drug abuse (especially cocaine)
- Certain medications, including some antidepressants and blood
pressure medications
- Spinal cord problems
- Injury to the genitals
- Anesthesia
- Penile injection therapy (a treatment for erectile dysfunction)
- Blood diseases, including leukemia and sickle cell anemia
Treatment for priapism is important, because a prolonged erection can scar
the penis if not treated. The goal of treatment is to relieve the erection and
preserve penile function. In most cases, treatment involves draining the blood
using a needle placed in the side of the penis. Medications that help shrink
blood vessels, which decreases blood flow to the penis, also may be used. In
rare cases, surgery may be required to avoid permanent damage to the penis. If
the condition is due to sickle cell disease, a blood transfusion may be
necessary. Treating any underlying medical condition or substance abuse
problem is important to preventing priapism.
Peyronie’s disease
Peyronie's disease is a condition in which a plaque, or hard lump, forms on
the penis. The plaque may develop on the upper (more common) or lower side of
the penis, in the layers that contain erectile tissue. The plaque often begins
as a localized area of irritation and swelling (inflammation), and can develop
into a hardened scar. The scarring reduces the elasticity of the penis in the
area affected.