Erectile Dysfunction

A man's penis becomes erect when one of his senses (sight, sound, taste, touch, or smell) is stimulated and he becomes aroused. His central nervous system sends nerve impulses that increase blood flow to his penis. As blood flows into the penis, the penis gets larger and harder. The blood vessels that drain blood from the penis are blocked enough so that blood stays in the penis, maintaining the erection.

Four things are needed to have a normal erection:

Damage to or problems with any of these things may lead to erectile dysfunction.

Psychological factors also may affect normal erectile function.

Blood flow and erection problems

There are two spongy chambers along each side of the shaft of your penis. These chambers are called the corpus cavernosa. When you have an erection, the smooth muscle in these spongy chambers relaxes so that blood flows in through the penile arteries and the chambers fill with blood and expand. The expanded chambers press against the veins that would normally drain blood from the penis, trapping the blood inside and making the penis erect.

After ejaculation or when you are no longer sexually aroused, the arteries narrow, the veins expand, and the blood drains out. The penis becomes limp.

Problems with the blood vessels that supply blood to the penis or return blood from the penis can cause erection problems. These vascular problems may include: