An erection is a very complex function as it depends on different mechanisms located at different levels. In simple terms, it can be said that erection begins with a sexual stimuli (visual, auditory, olfactory, mental, etc) influenced by testosterone (male hormone) which is integrated in the brain. In the brain a signal begins which travels down the spinal medulla, favouring the liberation of elements called neurotransmitters in the nerve endings of the penis. These neurotransmitters act on the tissue making up the cavernous bodies of the penis which consist, similar to a sponge, of a series of small cells (sinusoids) surrounded by muscle which, in a state of flaccidity is contracted and therefore the small cells are closed. The neurotransmitters, fundamentally nitrous oxide, make the musculature of the small cells relax, favouring the entry of blood into the penis and, therefore, leading to the rigidity of the penis.
Diagram of a cross-section of the penis
Skin
Superficial penile vessels
Buck’s fascia
Deep dorsal vein
Dorsal artery
Dorsal nerve
Cavernous body
Cavernous artery
Sinusoids
Corpus spongiosum and urethra
 |
 |
After ejaculation or when the sexual stimuli ceases, other elements such as adrenaline make the musculature of the small cells contract once more, pushing the blood out of the penis and returning to a state of flaccidity.
Therefore, different points of the brain, hormones (testosterone), the nerves that run down the spinal medulla to the penis, arteries, veins and the cavernous bodies all intervene in an erection.
What do we call erectile dysfunction (Impotence)?
The permanent or temporary inability to achieve and/or maintain an erection of sufficient quality to enjoy satisfactory sexual relations.
What are the causes affecting erection?
Anything that affects one or several of the elements that intervene in the erection may be the cause of erectile dysfunction. Along very general lines, we refer to organic causes when the vessels, nerves or cavernous bodies of the penis are affected and psychogenic causes when the origin is at brain level. In many cases there may be both organic and psychogenic causes in one same individual. Apart from the large number of psychogenic problems such as depression, a poor relationship, work problems or problems of any other nature, the very fact of not achieving a correct erection creates a concern that worsens the situation.
Within the organic causes, the most frequent are those that affect the blood vessels, making the entry of blood or maintaining blood in the penis difficult. This can be due to obstructions (arteriosclerosis), trauma or lesions of the arteries. Given that the penis is like a large blood vessel, it shares all the cardiocirculatory disease risk factors (high cholesterol, smoking, high blood pressure diabetes, obesity). On many occasions it is possible to uncover a significant illness such as high blood pressure or diabetes, the first manifestation of which is erectile dysfunction by affecting the small arterial vessels. If the illness progresses, it will subsequently affect the arteries of the heart. This is why it is important to study the causes of erectile dysfunction and thereby be able to prevent far more important general health problems.
Certain diseases, trauma or other nerve lesions may also cause erectile dysfunction. A common situation is that which takes place when there is a total removal of the prostate due to cancer. In these cases it is very difficult not to damage the erection nerves which adhere to the prostate.
Advanced age in itself is not a cause of erectile dysfunction, however, the condition is common in old age due to the illnesses presented by any given individual and the effect they may have on the erection.
There are many medications (antihypertensive, anti-depressant) drugs and other toxins that may affect the erection by acting on different levels.
Certain diseases of the penis such as the so-called Peyronie’s Disease (fibrosis of the penis) may also cause the dysfunction.
A reduction in testosterone primarily affects sexual desire, but it may also negatively affect the erection.
Apart from those mentioned, there are many other causes, both known and unknown, of erectile dysfunction.