Erection

An erection (clinically: penile erection or penile tumescence; informal/slang: stiffy, hard-on, boner and many others) is a physiological phenomenon of the male genitalia of many species, in which the penis becomes firmer, engorged and enlarged. Penile erection is the result of a complex interaction of psychological, neural, vascular and endocrine factors, and is usually, though not exclusively, associated with sexual arousal or sexual attraction. The shape, angle and direction of an erection varies considerably in humans.

Physiologically, erection is triggered by the parasympathetic division of the autonomic nervous system (ANS), causing nitric oxide (a vasodilator) levels to rise in the trabecular arteries and smooth muscle of the penis. The arteries dilate causing the corpora cavernosa of the penis (and to a lesser extent the corpora spongiosum) to fill with blood; simultaneously the ischiocavernosus and bulbospongiosus muscles compress the veins of the corpora cavernosa restricting the egress and circulation of this blood. Erection subsides when parasympathetic activity reduces to baseline.

As an autonomic response, erection may result from a variety of stimuli, including sexual stimulation and sexual arousal, and is therefore not entirely under conscious control. Erection during sleep or upon waking up are known as nocturnal penile tumescence (NPT). Absence of nocturnal erection is commonly used to distinguish between physical and psychological causes of erectile dysfunction and impotence.

A penis which is partly, but not fully, erect is sometimes known as a semi-erection (clinically: partial tumescence); a penis which is not erect is typically referred to as being flaccid, or soft.

Read more about Erection:  Physiology, Socio-sexual Aspects, In Non-human Animals, Terminology, See Also

Other articles related to "erection":

Biological Functions Of Nitric Oxide - Erection
... also plays a role in development and maintenance of erection ... of blood vessels supplying the corpus cavernosum results in more blood flowing in and hence erection ...
Archconfraternity - Status and Operation
... Canonical erection is the approval of the proper ecclesiastical authority which gives the organization a legal existence ... case, however, of many confraternities and archconfraternities, the power of erection is vested in the heads of certain religious orders ... in their own churches, the consent of the bishop given for the erection of the house or church of the order is sufficient ...
Human Sexual Response Cycle - Excitement Phase - Excitement in Males
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Erection - See Also
... Sexuality portal Clitoral erection Death erection Erectores pilorum Issues in social nudity Nipple erection Nocturnal penile tumescence Priapism ...
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... ability to do three things achieve an erection while on a busy and sometimes pressuring film set, maintain that erection while performing on camera, and then ejaculate on cue ... In the past an actor's inability to maintain an erection or being subject to premature ejaculation could make the difference between a film turning a ... If an actor loses his erection, filming is forced to stop for about 45 minutes whilst the drug takes effect ...