Impotence or Erectile Dysfunction (ED) is defined as the consistent inability to achieve and maintain an erection sufficiently to permit satisfactory sexual intercourse. Many men experience erectile failure one or more times during their adult lives (usually due to anger, stress or drinking) but this clears up quickly and no treatment is needed.
Since an erection requires a sequence of events, impotence can occur when any of the events is disrupted. The sequence includes nerve impulses in the brain, spinal column, and area of the penis, and response in muscles, fibrous tissues, veins, and arteries in and near the corpora cavernosa.
Experts believe that psychological factors cause 80 percent of cases of impotence. These factors include stress, anxiety, guilt, depression, low self-esteem, and fear of sexual failure.
Other possible causes of impotence are smoking, which affects blood flow in veins and arteries, and hormonal abnormalities, such as insufficient testosterone.