Impotence describes a condition in which a man cannot achieve or maintain an erection. Although an erection seems like a simple sexual response, it actually requires a specific sequence of events. An erection occurs due to a complex interaction between hormones, nerves, muscles and blood flow. Any condition, disease or outside force that interrupts any part of this process can result in impotence.
Mechanics
Sexual arousal triggers the brain to send nerve signals through the spinal cord to the neurovascular bundles near the prostate gland. These nerve signals stimulate the production and release of enzymes that trigger the smooth muscles surrounding the blood vessels in the penis to relax. Once these muscles relax, the blood vessels can dilate, allowing additional blood to flow in. The veins in the penis then constrict, holding the blood in the penis. An erect penis can hold 10 times the amount of blood it can hold when not erect, as described by the Prostate Cancer Treatment Guide.
Interruption
Anything that interrupts the flow of blood into the penis can cause impotence. Vascular diseases, such as arteriosclerosis---or hardening of the arteries, and atherosclerosis---the buildup of fatty tissue in the arteries, can impede the flow of blood into the penis. Chronic medical conditions that contribute to vascular disease, such as high blood pressure and diabetes, increase the risk of developing impotence, as reported in a study in the "Journal of Urology."
Certain medications, such as those prescribed to treat high blood pressure, can also inhibit the flow of blood required to obtain an erection. These include medications classified as beta blockers, such as propranolol and diuretics.
Interruption in Nerve Signals
Interrupting nerve signals between the brain, spinal cord and penis can also cause impotence. Damage to the spinal cord caused by trauma can impede nerve signals from reaching the neurovascular bundle. Neurological conditions and diseases such as multiple sclerosis, Parkinson's disease and Alzheimer's disease can also interrupt the nerve signals traveling from the brain to the penis. Medications, such as those classified as antidepressants, can also interrupt the transmission of nerve signals, therefore resulting in impotence.
Hormone Imbalances
Doctors know that testosterone, an androgen hormone important for male reproduction, plays a role in erectile function because as males age, testosterone levels decrease while erectile dysfunction increases. The extent of the relationship however, remains a matter of debate. Research published in the "Reviews in Urology" indicates that a low level of testosterone, a condition known as hypogonadism, contributes to a loss of libido, but still remains a rare cause of impotence.
Reproductive System Dysfuction
Conditions that affect the reproductive organs, including the prostate gland, can result in impotence. Treatments for prostate or testicular cancer can damage blood vessels and either impede the flow of blood or redirect it away from the penis. Peyronie's disease occurs when a flat plate of scar tissue forms on the top or bottom of the penis, reducing the flexibility of the penis, which can make sexual intercourse difficult. This can disrupt a couple's physical and emotional relationship, which reduces a man's self-esteem and can lead to impotence, as described by the National Kidney and Urologic Diseases Information Clearinghouse.
References
- Prostate Cancer Treatment Guide: Mechanics of an Erection
- National Kidney and Urologic Diseases Information Clearinghouse: Erectile Dysfunction
- "Journal of Urology"; "Impotence and Its Medical and Psychosocial Correlates"
- "Reviews in Urology"; "Relationship Between Testosterone and Erectile Dysfunction"; Dr. Rajfer; 2000
- National Kidney and Urologic Diseases Information Clearinghouse: Peyronie's Disease
