Erectile Dysfunction - In General:

In order to understand erectile dysfunction it is important to understand what happens when things go right:

The penis contains two chambers, called the corpora cavernosa, which run the length of the upper side of the penis (see figure 1 below). The urethra, which is the channel for urine and ejaculate, runs along the underside of the corpora cavernosa. A spongy tissue consisting of smooth muscles, fibrous tissues, spaces, veins, and arteries fill the two chambers of corpora cavernosa. A membrane, called the tunica albuginea, surrounds the corpora cavernosa. Veins located in the tunica albuginea drains blood out of the penis.

The Erection:
Erection begins with sexual stimulation. Sexual stimulation can be tactile (for example, by touching the penis), or mental (for example, by having sexual fantasies). Sexual stimulation generates electrical impulses along the nerves going to the penis and causes the nerves to release nitric oxide, which in turn increases the production of cyclic GMP (cGMP) in the smooth muscle cells of the corpora cavernosa. The cGMP causes the smooth muscles of the corpora cavernosa to relax, and allow rapid blood flow into the penis. The in-coming blood fills the corpora cavernosa, making the penis expand.

Sustaining Erections:

The pressure from the expanding penis compresses the veins (blood vessels that drain the blood out of the penis) in the tunica albuginea, helping to trap the blood in the corpora cavernosa, thereby sustaining erection. Erection is reversed when cGMP levels in the corpora cavernosa fall, causing the smooth muscles of the corpora cavernosa to contract, stopping the inflow of blood and opening veins that drain blood away from the penis. The levels of the cGMP in the corpora cavernosa fall because it is destroyed by an enzyme called phosphodiesterase type 5 (PDE5)

The ability to achieve and sustain erections require:

A healthy nervous system that conducts nerve impulses in the brain, spinal column, and penis,
Healthy arteries in and near the corpora cavernosa,
Healthy smooth muscles and fibrous tissues within the corpora cavernosa, and
Adequate levels of nitric oxide in the penis.

Erectile Dysfunction:
Erectile Dysfunction (E.D) is defined as the inability of a man to achieve or maintain an erection sufficient for sexual intercourse.

Most men experience it to a degree some time in their lives; usually by the age of 40 although a lot of men are usually too reticent to talk about E.D. with their doctors.

E.D. can be chronic and complete thus causing impotence. Some dysfunctions are brief or partial. Transient or inadequate erections may affect 50% of men between the ages of 40-70.
E.D. can affect men emotionally leading to low self-esteem and this can hinder or destroy relationships

For Further Information

Diagnosis
Causes
Treatment
How an erection Occurs
FAQ's