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Physiology or the functioning of an erection


Last week I described the anatomy of an erection and will now discuss the physiology or the functioning of an erection. This is important if we are to understand why certain prescriptions or over the counter (OTC) medications work. When an erection occurs, both the nerves and the blood vessels are involved.{{more}}

The nerves to the penis produce a substance in the penis that causes the blood vessels of the penis to open up thus allowing more blood to enter the penis. Remember in my first article I described the penis as two cylinders of vascular tissue, well indeed they are, so as blood enters these cylinders an erection begins to occur.

However, the walls of these cylinders are such that as the penis gets bigger they get thinner like a balloon. These walls also pinch the veins that allow the blood to leave the penis so blood flows in but not out of the penile cylinders. Eventually, the cylinders get “full” and the penis is maximally hardened or rigid. At this stage no more blood can flow into the penis or it will “burst” like a balloon. This does not happen because the wall of the cylinders are so strong that the pressure of the blood in the arteries are not enough to “burst the balloon”, instead the pressure is “checked” like the pressure in a closed hose attached to an open pipe. This is when it is described as “wood” or “iron”. This is the rigid stage of the erection. This is also the most dangerous phase for these reasons:

1. The penis being hardest can inflict most damage and by the same token incite most pleasure. In other words there is a thin line between pain and pleasure and some women actually describe it as “pleasurable pain”. This pleasurable pain is, however, not what I am talking about. Instead it is the damage that has my gynecology colleagues busy suturing lacerated vaginal vaults and cervices.

2. The penile cylinder wall is thinnest when it is most erect. This is also the time when most of the exuberant and acrobatic thrusting is done and if the penis is forcibly and accidentally bent, then this cylinder can tear and “break the wood”. In other words, the person can fracture or break his penis. If this happens, the man will feel a snap, the erection will disappear and the penis will swell massively as the blood leaks out from these erectile cylinders to the outer tissues under the skin.

3. If this rigid stage is prolonged abnormally long, the tissues in the cylinder will lose their oxygen supply as no new blood can get in and old blood cannot get out through these “pinched” veins. So after about 45-60 minutes of constant “jamming” most men, if they are not exhausted will experience penile discomfort and will eventually lose their erections. Certainly, men who have priapism (a purposeless, passionless, prolonged, painful penile erection) for more than 2-4 hours will have pain and the penile tissues can die after 6-8 hours of this condition. Priapism is seen in men with blood problems as sickle cell disease, leukemia, renal failure and men who take certain medications like Viagra and OTC erectile stimulants like “mega man” and “stud 500” and “horny goat weed”. That’s why the ads for Viagra, Levitra and Cialis warn of priapism with the use of these medications.

My last point about the functioning of an erection has to do with the life of the penis. I mentioned above that a prolonged erection in the rigid phase can be dangerous because of lack of “new blood” flowing into the penis to keep the penile tissues alive. The same can be said of the flaccid state when the blood supply into the penis is just a trickle not zero as in the rigid state. So the penis can remain flaccid for hours, days or months without any harm, however, this trickle of blood flowing through the erectile tissues in this state is not very rich in oxygen and over a long period of time with no sexual activity, the erectile tissues begin to atrophy or get smaller. This is a case of if you do not use it, you lose it. Nature has provided for this disuse shrinkage by night time erections while you are sleeping. In other words even when you are not sexually active for a period of time, the body has its way of keeping the penile tissues healthy by nocturnal erections. It is therefore reasonable to assume that erections are not only natural and normal, but essential to the life and the function of the penis. It is also no small wonder that I have noticed in my urological practice that older men with large penises are also the men who appear to have a lot of children! This is just my observation and is not scientific proof that all men with lots of children have large penises. A possible connection could have been that because of a large penis he became “the village ram” and hence fathered a lot of children or maybe because of constant use with many women it became large. This might be a chicken and egg situation.

As one might expect penile size is not just a matter of use (after all it is a muscle, and constant exercise leads to increase in size) but genetics.

Large size should not be confused with ability to use as we have all heard the saying that “It is not the size of the ship, but it is the motion in the ocean,” and as an old reggae artist once said “It’s a pity they didn’t know it’s not the size of the gun but it’s the effect of the bullet”!

For comments or question contact:

Dr. Rohan Deshong

Tel: (784) 456-2785

email: [email protected]