Physiology of an Erection

The penis is composed of three different regions: a pair of parallel spongy columns called the corpora cavernosum and the central corpora spongiosum, which contains the urethra. Penile regions are made up of tissues which are known as erectile tissues. Erectile tissue is rich in blood vessels called cavernous sinuses. Cavernous sinuses are surrounded by smooth muscles and are supported by elastic fibrous tissues.i Erection is stimulated by the corpora cavernosa which comes from prostrate gland. When penis is flaccid, the small arteries in the cavernous sinuses shrink, and reduce the blood inflow.

At the time of arousal, the central nervous system stimulates the release of number of chemicals that relax the muscles in the penis, thus allowing the blood flow into sinuses. Once the blood rushes to the penis and leads to an erection occurs.
 

Erectile Dysfunction

Erectile dysfunction (or impotence) is the inability to achieve or maintain an erection that is sufficient to ensure satisfactory sexual intercourse for both partners. There are many degrees of erectile dysfunction ranging from a total inability to achieve/maintain an erection, an inconsistent ability to achieve/maintain an erection to a tendency to maintain only brief erections. Based on these, it has been reported that about 30 million men in the USA suffer from some form of ED.
 

Causes of Erectile Dysfunction

Erectile Dysfunction can occur if any of the events in the sequence leading to an erection are interrupted. The problem may stem from following factors:
 

Erectile Dysfunction Analysis

The first step conducted by a physician is a comprehensive examination to determine when and how the condition might have developed, other physical and psychological conditions and medications taken, if any. If an evident physical cause is suspected, blood tests are first taken to check hormonal levels and to eliminate probable diseases from the list discussed above.
 

Additional specialized clinical tests may also be done:

Penile nerve function:
This test is done to determine the nerve sensation to the penis.

Ultrasonography:
It evaluates the adequacy of arterial circulation in the penis. This test is conducted before and after injecting an external medication to check if the blood flow to penis gets any better.

Nocturnal Penile Tumescence (NPT):
Men experience five to six erections during the night, in their sleep. If any man fails to obtain so then it may point to some problem with nerve function or arterial circulation in the genital area. Rigidity and girth of the penis are studied by various means during nocturnal erections.

Cavernosometry:
This test is done to determine the vascular pressure in the penis.