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Médecine de la Reproduction

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Erection: How it works Volume 13, supplement 1, Décembre 2011

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Hôpital Carremeau, Service d’uro-andrologie, place du Pr Debré, 30029 Nîmes Cedex, France

Erection is a neurovascular, tissue related phenomenon. The penile arteries (dorsal and cavernous) relax or contract in synchrony with aerial smooth muscle fibers (SMF). This is an active phenomenon, secondary to the action of neurotransmitters at intrapenian nerve endings. The penis is normally flaccid, and erection occurs only upon sexual stimulation. When flacid, the SMFs are not relaxed, but to the contrary are contracted due to a continuous, orthosympathic stimulation. During normal sexual activity, erection is primarily psychogenic and arises from sexual desire. A normal erection is complete, rigid and allows penetration and full sexual intercourse. Stimulation of the penis during intercourse allows mechanisms, which control the erection reflex to participate in its maintenance until ejaculation. The erection reflex is also a possible means of substitution, used to strengthen an incomplete psychogenic erection.