An erection of the penis occurs when two tubular structures that run the length of the penis, the corpora cavernosa, become engorged with venous blood. This may result from any of various stimuli. The corpus spongiosum is a single tubular structure located just below the corpora cavernosa, which contains the urethra, through which urine and semen pass during urination and ejaculation, respectively. This may also become slightly engorged with blood, but less so than the corpora cavernosa. Penile erection usually results from sexual stimulation and/or arousal, but can also occur by such causes as a full urinary bladder or spontaneously, most commonly during erotic or wet dreams. An erection results in swelling and enlargement of the penis or the swelling of the female counterpart to the penis, clitoris. Erection enables sexual intercourse and other sexual activities, though it is not essential for all sexual activities. The penis (plural penises or penes) or phallus is an external male sexual organ. ... A corpus cavernosum is one of a pair of a sponge-like regions of erectile tissue which contain most of the blood in the male penis during erection. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A nocturnal emission is an ejaculation of semen experienced by males during sleep. ... A womans clitoris extends from the visible portion to a point below the pubic bone. ... Coition of a Hemisected Man and Woman (c. ... Sexual behavior is a form of physical intimacy that may be directed to reproduction (one possible goal of sexual intercourse) and/or to the enjoyment of activity involving sexual gratification. ...

In addition to sexual arousal, erection in males can be caused by mechanical stimulation, or by the pressure of the filled urinary bladder. Erections when waking up are common, most likely due to a full bladder. They sometimes already occur in infant boys, and in utero. Recently some scientists have begun to doubt this very much (sources: see below). The question why most men have erections when waking up ("morning wood") is still not settled. The interior of bladder. ... In Utero is the third and final studio album from the American grunge band, Nirvana. ...

Mechanism

An uncircumcised penis in both flaccid and fully erect states, respectively.

A circumcised penis in both flaccid and fully erect states, respectively.

Physiologically, an erection is achieved by two mechanisms that play together: increased inflow of blood into the vessels of erectile tissue, and decreased outflow. The vessel system involved is known as the corpora cavernosa and the corpus spongiosum. Muscles in the region relax, allowing more blood to enter these sponge-like tissues. Contraction of other muscles reduce the outflow of blood from the penis. The enlarged structure then exerts pressures on the exit veins, further reducing the outflow. Image File history File linksMetadata Download high resolution version (3528x1700, 897 KB) Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File linksMetadata Download high resolution version (3528x1700, 897 KB) Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File linksMetadata Download high resolution version (1097x487, 73 KB) Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File linksMetadata Download high resolution version (1097x487, 73 KB) Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... The arterial system The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... Erectile tissue is tissue in the body that can become erect, usually by becoming engorged with blood. ... A corpus cavernosum is one of a pair of a sponge-like regions of erectile tissue which contain most of the blood in the male penis during erection. ... Corpus spongiosum (Plural: Corpora Spongiosa) is the mass of spongy tissue surrounding the male urethra within the penis. ... A top-down view of skeletal muscle Muscle is the contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. ... Vein - Wikipedia, the free encyclopedia /**/ @import /skins-1. ...

As blood flows in, the penis stiffens, its girth and length increase and it rises to an angle that can vary between individuals from below horizontal to almost vertical.

Certain conditions (e.g. diabetes mellitus) result in erectile dysfunction, a problem where penile erection is insufficient to achieve normal sexual intercourse. In recent years, several drugs have been developed for treatment of this condition. For the disease characterized by excretion of large amounts of severely diluted urine, see diabetes insipidus. ... Erectile dysfunction or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis for satisfactory sexual intercourse regardless of the capability of ejaculation. ...

If present, the foreskin normally retracts and exposes the glans. The skin of the scrotum tightens, pulling the testicles in towards the base of the penis. The Male Anatomy The foreskin or prepuce is a retractable double-layered fold of skin and mucous membrane that covers the glans penis and protects the urinary meatus when the penis is not erect. ... The glans penis is the sensitive erectile tip of the penis. ...

Erection is caused by signals from the parasympathetic nervous system; it is countered by the sympathetic nervous system which is mainly responsible for the "fight-or-flight" response. This explains why under stressful conditions, an erection is often difficult or impossible to achieve, and sudden onset of stress can deprive one of erection. The sympathetic nervous system is also responsible for causing ejaculation, which explains why most males lose their erection after ejaculation. It has been suggested that Parasympatholytic be merged into this article or section. ... Grays FIG. 838– The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Erection may occur spontaneously in the absence of any specific sexual stimulation, particularly in adolescent males. All men who are physically able to achieve an erection do so during sleep, typically several times in a night. This fact is utilized by sexual health practitioners to ascertain whether cases of erectile dysfunction are psychological or physiological in nature. Patients presenting with impotence are fitted with an elastic device worn around the penis which detects changes in girth and relays the information to a computer for later analysis. Men who obtain spontaneous erections in their sleep but not during waking hours are therefore considered to suffer from some form of psychosomatic condition, i.e. sexual anxiety disorder, which prevents them performing sexually.

Masturbation has no negative impact of erectile function besides a reduction in sex drive in a way exactly homologous to sexual intercourse. Masturbation is the manual excitation of the sexual organs, most often to the point of orgasm. ...

In some cases penile erection may occur even after death, if pressure within the penis increases for some reason, for example due to sinking fluids or the formation of gases of putrefaction. See death erection. Putrefaction is the decomposition of proteins, especially by anaerobic microorganisms. ... A death erection (sometimes referred to as angel lust) is a post-mortem erection which occurs when a male individual dies vertically or face-down with the cadaver remaining in this position. ...

The clitoris of females contains erectile tissue and becomes erect during sexual arousal. Erection of the clitoris is exactly analogous to male penile erection only less visible due to the relatively discreet anatomical positioning of the clitoris. A womans clitoris extends from the visible portion to a point below the pubic bone. ... The mirror of the Roman Goddess Venus is often used to represent the female sex. ... Erectile tissue is tissue in the body that can become erect, usually by becoming engorged with blood. ...

Erection of nipples, however, is not due to erectile tissue. In its most general form, a nipple is an appurtenance from which a fluid emanates, in this instance breast milk, to nurture a mothers young. ...

Dysfunction

Failure of the erection mechanism is known as erectile dysfunction, or ED for short. ED in humans is treated with prosthetic devices, and with prescription drugs. Some prescription drugs are injected directly into the corpus cavernosum or used as urethral suppositories, directly causing erection even in the absence of sexual excitation, while others, such as Viagra, Cialis, or Levitra are taken orally and support erection that is due to sexual excitation. Erectile dysfunction or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis for satisfactory sexual intercourse regardless of the capability of ejaculation. ... A United States soldier demonstrates Foosball with two prosthetic limbs In medicine, a prosthesis is an artificial extension that replaces a missing part of the body. ... A suppository is a medicine that is inserted either into the rectum (rectal suppository) or into the vagina (vaginal suppository) where it melts. ... Sildenafil citrate, sold under the name Viagra, is a drug used to treat male erectile dysfunction (impotence), developed by the pharmaceutical company Pfizer. ... Categories: PDE5 inhibitors | Stub | Sexology ... Categories: Pages needing attention | Medicine stubs | Sexology | PDE5 inhibitors ...

Occasionally, the foreskin of the erect penis may be very tight and immobile on the shaft, thus interfering with normal erection. This condition is known as phimosis, however it is usually very easily treatable. The Male Anatomy The foreskin or prepuce is a retractable double-layered fold of skin and mucous membrane that covers the glans penis and protects the urinary meatus when the penis is not erect. ... Phimosis is a medical condition in which the foreskin of the penis of an uncircumcised male cannot be fully retracted. ...

Culture

In several countries, movies and magazines available to juveniles may not depict erections; such depictions are often taken as one criterion to distinguish between soft and hard pornography. Pornographic movies Pornography (from Greek πορνη prostitute and γραφία written material) (also informally referred to as porn, pr0n, or porno) is the representation of the human body or human sexual behaviour with the goal of sexual arousal, similar to, but distinct from, erotica, though the two terms are often used interchangeably. ...

Slang

As with nearly any aspect of the human body that is involved in sex, there are many slang words for an erection. Some of these are noted in the bathroom humor article. Toilet humour (also potty humour) is a type of humour dealing with bodily toilet functions. ...

For slang terms for the "erection", see WikiSaurus:erection — the WikiSaurus list of synonyms and slang words for erections in many languages.

Some terms would be (in alphabetical order): blood sport, boner, hard-on, johnson, love truncheon, pecker, peter, stiffy, wang, woody. Slang is the non-standard or non-dialectal use of words in a language of a particular social group, and sometimes the creation of new words or importation of words from another language. ... Wiktionary is a Wikimedia Foundation project intended to be a free wiki dictionary (hence: Wiktionary) (including thesaurus and lexicon) in every language. ...

Note that most of the foregoing are restricted to North American (particularly U.S.) usage, with the exception of hard-on (hardon) and stiffy, although boner is gaining ground in Commonwealth English.

Bibliography

• Harris, Robie H. (et al.), It's Perfectly Normal: Changing Bodies, Growing Up, Sex And Sexual Health. Boston, 1994. (ISBN 1564021998)

• Milsten, Richard (et al.), The Sexual Male. Problems And Solutions. London, 2000. (ISBN 0393321274)

• Tanagho, Emil A. (et al.), Smith's General Urology. London, 2000. (ISBN 0838586074)

• Williams, Warwick, It's Up To You: Overcoming Erection Problems. London, 1989. (ISBN 072251915X)

See also

• Priapism
• Death erection
• Foreskin

Priapism (Greek πριαπισμός, the erection) is a painful and potentially harmful medical condition in which the erect penis (erection) does not return to its flaccid state (despite the absence of both physical and psychological stimulation). ... A death erection (sometimes referred to as angel lust) is a post-mortem erection which occurs when a male individual dies vertically or face-down with the cadaver remaining in this position. ... The Male Anatomy The foreskin or prepuce is a retractable double-layered fold of skin and mucous membrane that covers the glans penis and protects the urinary meatus when the penis is not erect. ...

External links

• Photographs of several different erections by size, shape, angle, etc. from a photographic scientific study (The images are explicit, but scientifically presented, rather than pornography)