Erectile Dysfunction

Physiology of an Erection

Achieving and maintaining an erection depends on a complex interaction of the body's nervous system and the vascular system in the penis. The following is a simplified explanation of how a male achieves and maintains an erection.

The erectile response typically begins in the brain. Responding to sexual stimulation, the brain initiates neurological response to increase blood flow in the corpus cavernosal arteries within the penis. With the increase in blood flow, the corpus cavernosum surrounding each artery and begins to fill with blood.

The corpus cavernosum consists of “sponge like” tissue which runs the length of the penis. As the corpus cavernosum fills with blood, they expand and begin to press against the body of the penis. This pressure closes the veins reducing their ability to carry blood away from the penis.

The reduction in venous blood flow, known as venous occlusion, allows blood to be trapped in the corpus cavernosum. This process continues until the pressure in the corpus cavernosum equals the pressure of the corpus cavernosal arteries. It is at this point that the penis is fully erect.

The process of achieving an erection depends on the proper functioning of the following:

• Nervous system
• Corpus Cavernosal Arteries
• Corpus Cavernosum Tissue
• Occlusion of veins in the penis

If any of these areas of the body are not functioning or are not completely functional, this can cause erectile dysfunction. Erectile dysfunction, commonly known as impotence, is defined as “the inability of a male to attain and maintain erection of the penis sufficient to permit satisfactory sexual intercourse.”

Aging-Related Changes

In young men, the higher centers of the brain are easily stimulated by fantasizing or thinking about sex which seems to cause an erection nearly at will. With aging, this ability decreases. Ability to reach arousal with suggestive photographs also becomes less effective, although arousal by viewing a suggestive video may remain longer. Increased interaction of the couple, especially with foreplay, is needed to achieve a satisfactory erection.

Another age-related change is an increase in the refractory period — that is, the time from ejaculation to the next erection. This interval may range from 30 minutes in a young man to several days in an octogenarian, according to the work of Masters and Johnson.

Erections, once achieved through fantasy and foreplay, are more fragile as men age. Older men must maintain their focus; if they allow themselves to be distracted by thinking of work or other activities, detumescence (loss of an erection) may occur. The ringing of the telephone may be enough to cause detumescence. In addition, men may occasionally experience detumescence without ejaculation for no apparent reason.

Testosterone Levels

The effect of low levels of the male sex hormone testosterone on erectile function is not clear. Studies have shown that low testosterone levels do not necessarily prevent a man from having an erection. Low testosterone levels, however, can decrease sexual desire.

The nature of the problem causing erectile dysfunction may be determined by using the NEVA System or Knoll/MIDUS System.