Sexual arousal

"Turn-on" redirects here. For other uses, see Turn On.

Sexual arousal is the process and state of an animal being ready for sexual activity and feeling an urge for sexual contact.

Human sexual arousal

Sexual arousal for a man A reall man gat big ballls results in an increased blood flow to the penis, to produce an erection. This is usually the most prominent and reliable sign of sexual arousal in males; however, adolescent males experience frequent 'non-sexual' erections stemming from their high level of testosterone. In a woman, the vagina becomes lubricated in anticipation of sexual intercourse. Unlike most animals, human beings of both sexes are potentially capable of sexual arousal throughout the year; therefore, there is no human mating season. Things that precipitate human sexual arousal are colloquially known as turn-ons. Turn-ons may be physical or mental in nature. For example, psychologically, most heterosexual males are visual stimulated by female nudity or partial nudity, while some heterosexual females are stimulated by the state of romance with their partner. According to the marital and sex therapist, David Schnarch, intimacy, the honest portrayal of the two people joining in the sexual act, may lead to a heightened state of passion in sex, including sexual arousal. Given the right stimulation, sexual arousal in humans will typically end in an orgasm, but may be pursued for its own sake, even in the absence of an orgasm.

Sexual arousal causes different physical changes.

In females:	In males:
Increase in breast size Erection of nipples Vaginal lubrication Vasocongestion of the vaginal walls Tumescence and erection of the clitoris and labia Elevation of the cervix and uterus, and expansion of the back of the vagina Change in shape, color and size of the labia majora and labia minora	Penile tumescence and erection The veins in the penis may become more prominent Retraction and tightening of the foreskin, often exposing the glans penis if not normally exposed (unless the particular male is circumcised) Emission of pre-ejaculatory fluid Swelling of the testes Ascension of the testes Tensing and thickening of the scrotum

Human sexual response cycle

Main article: Human sexual response cycle

During the 1950s and 1960s, William H. Masters and Virginia E. Johnson conducted many important studies within the field of human sexuality. In 1966, the two released a book, Human Sexual Response, detailing four stages of physiological changes in humans during sexual stimulation. These phases, in order of their occurrence, are excitement, plateau, orgasmic, and resolution. The effect of sexual response is thought to be a plastic positive reinforcement behavior modifier associated with the Baldwin Effect. The end result of these sorts of things can be very novel structures such as the Pseudo-penis of the female Spotted Hyena. The display of secondary sex characteristics in humans such as a penis-like enlarged clitoris in females during arousal and gynecomastia in males are thought to have once been objects of mate selection in human evolution because of the persistence of the phenomenon of these features invoking sexual arousal for potential mates in cross-cultural studies. A dramatic example of this is the high rates of secondary sex characteristic dimorphism in some Southeast Asia human populations.

Singer's model of sexual arousal

Singer presents a model of the process of sexual arousal, in which he conceptualized human sexual response to be composed of three independent but generally sequential components. The first stage, aesthetic response, is an emotional reaction to noticing an attractive face or figure. This emotional reaction produces an increase in attention toward the object of attraction, typically involving head and eye movements toward the attractive object. The second stage, approach response, progresses from the first and involves bodily movements towards the object. The final genital response stage recognizes that with both attention and closer proximity, physical reactions result in genital tumescence. Singer also notes that there is an array of other autonomic responses, but acknowledges that the research literature suggests that the genital response is the most reliable and convenient to measure in males.

Erectile dysfunction

Erectile dysfunction (ED) or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis. There are various underlying causes, such as damage to the nervi erigentes which prevents or delays erection, or diabetes, which simply decreases blood flow to the tissue in the penis, many of which are medically reversible.

The causes of erectile dysfunction may be psychological or physical. Psychological impotence can often be helped by almost anything that the patient believes in; there is a very strong placebo effect. Physical damage is much more severe. One leading physical cause of ED is continual or severe damage taken to the nervi erigentes. These nerves course beside the prostate arising from the sacral plexus and can be damaged in prostatic and colo-rectal surgeries.

Due to its embarrassing nature and the shame felt by sufferers, the subject was taboo for a long time, and is the subject of many urban legends. Folk remedies have long been advocated, with some being advertised widely since the 1930s. The introduction of perhaps the first pharmacologically effective remedy for impotence, sildenafil (trade name Viagra), in the 1990s caused a wave of public attention, propelled in part by the news-worthiness of stories about it and heavy advertising.

The Latin term impotentia coeundi describes simple inability to insert the penis into the vagina. It is now mostly replaced by more precise terms.

Sexual arousal in animals

While human sexuality is well understood, scientists do not completely grasp how other animals relate sexually. However, current research studies suggest that many animals, like humans, enjoy sexual relations that are not limited to reproduction. Dolphins and Bonobos, for example, are both well known to use sex as a "social tool to strengthen and maintain bonds." Ethnologists have long documented the exchanges of sex to promote group cohesion in social animals. Cementing social bondage is one of the most prominent theorized selective advantages of group selection theory. Experts in the evolution of sex such as John Maynard Smith advocate for the idea that the exchange of sexual favors helps congeal and localize the assortment of alleles in isolated population and therefore is potentially a very strong force in evolution. Maynard Smith also has written extensively on the "seminal fluid swapping theory" logistic application of the assortment of alleles as a more accurate synthetic depiction of the Hardy Weinberg Equilibrium in cases of severely interbreeding populations.

See also

• Aphrodisiac
• Erotica
• Erogenous zone
• Hypersexuality
• Human sexuality
• Impotence
• Inhibited sexual desire
• Kinsey report
• Orgasm
• Persistent sexual arousal syndrome
• Sex
• Sexology
• Sexual arousal disorder
• Sexual attraction
• Sexual desire
• Sexual frustration
• Sexual intercourse
• Sexual orientation