Erectile dysfunction pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Pathophysiology
Penile erection is managed by two different mechanisms. The first one is the reflex erection, which is achieved by directly touching the penile shaft. The second is the psychogenic erection, which is achieved by erotic or emotional stimuli. The former uses the peripheral nerves and the lower parts of the spinal cord, whereas the latter uses the limbic system of the brain. In both conditions an intact neural system is required for a successful and complete erection. Stimulation of penile shaft by the nervous system leads to the secretion of nitric oxide (NO), which causes the relaxation of smooth muscles of corpora cavernosa (the main erectile tissue of penis), and subsequently penile erection. Additionally, adequate levels of testosterone (produced by the testes) and an intact pituitary gland are required for the development of a healthy male erectile system. As can be understood from the mechanisms of a normal erection, impotence may develop due to hormonal deficiency, disorders of the neural system, lack of adequate penile blood supply or psychological problems. Restriction of blood flow can arise from impaired endothelial function due to the usual causes associated with coronary artery disease, but can also include causation by prolonged exposure to bright light or chronic exposure to high noise levels.
A few causes of impotence may be iatrogenic (medically caused). Various antihypertensives (medications intended to control high blood pressure) and some drugs that modify central nervous system response may inhibit erection by denying blood supply or by altering nerve activity.
Surgical intervention for a number of different conditions may remove anatomical structures necessary to erection, damage nerves, or impair blood supply.Complete removal of the prostate gland or external beam radiotherapy of the gland are common causes of impotence; both are treatments for advanced prostate cancer. Some studies have shown that male circumcision may result in an increased risk of impotence,[1][2] while others have found no such effect,[3][4][5] and another found the opposite.[6]
Excessive alcohol use has long been recognised as one cause of impotence, leading to the euphemism "brewer's droop," or "whiskey dick;" Shakespeare made light of this phenomenon in Macbeth.
A study in 2002 found that ED can also be associated with bicycling. The number of hours on a bike and/or the pressure on the penis from the saddle of an upright bicycle is directly related to erectile dysfunction.[7]
References
- ↑ Palmer J, Link D (1979). "Impotence following anesthesia for elective circumcision". JAMA. 241 (24): 2635–6. PMID 439362. - Reproduced at www.cirp.org Circumcision Information and Resource Pages
- ↑ Shen Z, Chen S, Zhu C, Wan Q, Chen Z (2004). "[Erectile function evaluation after adult circumcision]". Zhonghua Nan Ke Xue. 10 (1): 18–9. PMID 14979200.
- ↑ Senkul T, IşerI C, şen B, KarademIr K, Saraçoğlu F, Erden D (2004). "Circumcision in adults: effect on sexual function". Urology. 63 (1): 155–8. PMID 14751371. - Reproduced at www.cirp.org Circumcision Information and Resource Pages
- ↑ Collins S, Upshaw J, Rutchik S, Ohannessian C, Ortenberg J, Albertsen P (2002). "Effects of circumcision on male sexual function: debunking a myth?". J Urol. 167 (5): 2111–2. PMID 11956452. - Reproduced at www.cirp.org Circumcision Information and Resource Pages
- ↑ Masood S, Patel H, Himpson R, Palmer J, Mufti G, Sheriff M (2005). "Penile sensitivity and sexual satisfaction after circumcision: are we informing men correctly?". Urol Int. 75 (1): 62–6. PMID 16037710.
- ↑ Laumann E, Masi C, Zuckerman E (1997). "Circumcision in the United States. Prevalence, prophylactic effects, and sexual practice". JAMA. 277 (13): 1052–7. PMID 9091693. - Reproduced at www.cirp.org Circumcision Information and Resource Pages
- ↑ Schrader S, Breitenstein M, Clark J, Lowe B, Turner T (2002). "Nocturnal penile tumescence and rigidity testing in bicycling patrol officers". J Androl. 23 (6): 927–34. PMID 12399541. Unknown parameter
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