Over the last several years, we have gained a much better understanding of the physiology of erectile function. This understanding has led to the development of many of the treatments that we are all so familiar with.
An erection occurs when the two erectile bodies of the penis known as the corpora cavernosum fill with blood. As the corpora fill with blood the penis becomes engorged. In order for the erection to proceed to maximum rigidity, the blood must be trapped by sinusoids (venous structures within the corpora) and additional venous structures that are also compressed by the expansion that occurs. Erectile dysfunction can occur as a result of inadequate inflow of blood. An alternative mechanism of erectile dysfunction can occur if the venous structures do not trap the blood. An analogy would be trying to fill the bathtub (arterial inflow) which will not fill up if the drain is not closed (venous outflow). As the blood fills the penis, there is a change in the width and length of the penis.
A complex network of nerves is involved with the erectile process. Both the autonomic (sympathetic and parasympathetic) and somatic (motor and sensory) nervous systems are involved. A series of stimuli occur with sexual stimulation that ultimately leads to an erection.
These neural pathways ultimately cause a biochemical cascade of events that leads to the release of nitric oxide during sexual stimulation. This substance causes the activation of an enzyme that leads to increased levels of the substance cyclic guanosine monophospate (cGMP). cGMP results in the relaxation of the smooth muscle of the penis allowing the inflow of blood to occur that initiates the changes in rigidity leading to erection. By altering levels of nitric oxide, pharmaceutical manufacturers have come across a mechanism to medically treat erectile dysfunction.
Published On: July 24, 2006