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Erectile dysfunction (impotence) is the inability to achieve or maintain an erection sufficiently rigid for sexual intercourse. Sexual drive and the ability to have an orgasm are not necessarily affected. Because all men have erection problems from time to time, doctors consider erectile dysfunction to be present if attempts at intercourse fail at least 25% of the time.
Erectile dysfunction is not new in either medicine or human experience, but it is not easily or openly discussed. Cultural expectations of male sexuality inhibit many men from seeking help for a disorder that can usually benefit from medical treatment.
The Structure of the Penis. The penis is composed of the following structures:
These structures are made up of erectile tissue. Erectile tissue is rich in tiny pools of blood vessels called cavernous sinuses. Each of these vessels are surrounded by smooth muscles and supported by elastic fibrous tissue composed of a protein called collagen.
Erectile Function and Nitric Oxide. The penis is either flaccid or erect depending on the state of arousal. In the flaccid, or unerect, penis, the following normally occurs:
During arousal the following occurs:
A proper balance of certain chemicals, gases, and other substances is critical for erectile health.
Collagen. The protein collagen is the major component in structural tissue in the body, including in the penis. Excessive amounts, however, form scar tissue, which can impair erectile function.
Oxygen. Oxygen-rich blood is one of the most important components for erectile health. Oxygen levels vary widely from reduced levels in the flaccid state to very high in the erect state. During sleep, a man can normally have three to five erections per night, bringing oxygen-rich blood to the penis.
Testosterone and Other Hormones. Normal levels of hormones, especially testosterone, are essential for erectile function, though their exact role is not clear.
The primary cause of oxygen deprivation is ischemia -- the blockage of blood vessels. The same blood flow-reducing conditions that lead to heart disease, such as atherosclerosis, may also contribute to erectile dysfunction. Conditions such as unhealthy cholesterol levels, diabetes, and high blood pressure are associated with atherosclerosis and heart disease.
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