Orgasm

[2] The period after orgasm (known as the resolution phase) is typically a relaxing experience after the release of the neurohormones oxytocin and prolactin, as well as endorphins (or "endogenous morphine").

[3] Human orgasms usually result from physical sexual stimulation of the penis in males (typically accompanied by ejaculation) and of the clitoris (and vagina) in females.

In one controlled study by Vance and Wagner (1976), independent raters could not differentiate written descriptions of male versus female orgasm experiences".

[30] With regard to specific density of nerve endings, while the area commonly described as the G-spot may produce an orgasm,[2][31] and the urethral sponge (area in which the G-spot may be found) runs along the "roof" of the vagina and can create pleasurable sensations when stimulated, intense sexual pleasure (including orgasm) from vaginal stimulation is occasional or otherwise absent because the vagina has significantly fewer nerve endings than the clitoris.

[2][4][34][35] Sex educator Rebecca Chalker states that only one part of the clitoris, the urethral sponge, is in contact with the penis, fingers, or a dildo in the vagina.

[29][31][56][57] In their 2009 published study, the "coronal planes during perineal contraction and finger penetration demonstrated a close relationship between the root of the clitoris and the anterior vaginal wall".

"[33] Commenting on Komisaruk's research and other findings, Emmanuele A. Jannini, a professor of endocrinology at the University of Aquila in Italy, acknowledges a series of essays published in March 2012 in The Journal of Sexual Medicine, which document evidence that vaginal and clitoral orgasms are separate phenomena that activate different areas of the brain and possibly suggest key psychological differences between women.

[4][10][20] Scholars state "many couples are locked into the idea that orgasms should be achieved only through intercourse [vaginal sex]" and that "[e]ven the word foreplay suggests that any other form of sexual stimulation is merely preparation for the 'main event.

[81] A scientific study to successfully document natural, fully ejaculatory, multiple orgasms in an adult man was conducted at Rutgers University in 1995.

[2][16] The prostate is the male homologue (variation) to the Skene's glands (which are believed to be connected to the female G-spot),[84] and can be sexually stimulated through anal sex, perineum massage or a vibrator.

[40][42][101] Women's orgasms have been estimated to last on average approximately 20 seconds and to consist of a series of muscular contractions in the pelvic area that includes the vagina, the uterus, and the anus.

[102] For some women, on some occasions, these contractions begin soon after the woman reports that the orgasm has started and continue at intervals of about one second with initially increasing and then reducing intensity.

[106] Since ancient times in Western Europe, women could be medically diagnosed with a disorder called female hysteria, the symptoms of which included faintness, nervousness, insomnia, fluid retention, heaviness in abdomen, muscle spasm, shortness of breath, irritability, loss of appetite for food or sex, and "a tendency to cause trouble".

[107] Women considered to have the condition would sometimes undergo "pelvic massage:" stimulation of the genitals by the doctor until the woman experienced "hysterical paroxysm" (i.e., orgasm).

[118] A follow-up in 2001 which focused more specifically on cardiovascular health found that having sex three or more times per week was associated with a 50 percent reduction in the risk of heart attack or stroke.

There is some research suggesting that greater resting heart rate variability is associated with orgasms through penile-vaginal intercourse without additional simultaneous clitoral stimulation.

[29] A small percentage of men have a disease called postorgasmic illness syndrome (POIS), which causes severe muscle pain throughout the body and other symptoms immediately following ejaculation.

[4] Like Kinsey, scholars such as Peplau, Fingerhut, and Beals (2004) and Diamond (2006) found that lesbians have orgasms more often and more easily in sexual interactions than heterosexual women do,[4] and that female partners are more likely to emphasize the emotional aspects of lovemaking.

Specifically, with simultaneous orgasm and similar practices, many sexologists claim that the problem of premature ejaculation[135] is closely related to the idea encouraged by a scientific approach in the early 20th century when mutual orgasm was overly emphasized as an objective and a sign of true sexual satisfaction in intimate relationships.Menopause may involve loss of hormones supporting sexuality and genital functionality.

"[10] Desmond Morris suggests in his 1967 popular science book The Naked Ape that the female orgasm evolved to encourage physical intimacy with a male partner and help reinforce the pair bond.

[9][22][49] For example, it has been suggested that the 30 percent reduction in the size of the vagina could help clench the penis (much like, or perhaps caused by, the pubococcygeus muscles), which would make it more stimulating for the male (thus ensuring faster or more voluminous ejaculation).

The British biologists Baker and Bellis have suggested that the female orgasm may have a peristalsis or "upsuck" action (similar to the esophagus' ability to swallow when upside down), resulting in the retaining of favorable sperm and making conception more likely.

During her orgasm, her pelvic muscles contracted and her cervix repeatedly dipped into a pool of semen in the vaginal fornix, which might ensure that sperm would proceed by the external orifice of the uterus, making conception more likely.

[149] Though Dixson classifies humans as mildly polygynous in his survey of primate sexuality, he appears to have doubts, when he writes, "One might argue that ... the female's orgasm is rewarding, increases her willingness to copulate with a variety of males rather than one partner, and thus promotes sperm competition."

[27][28] While researchers such as Geoffrey Miller, Helen Fisher, Meredith Small and Sarah Blaffer Hrdy "have viewed the clitoral orgasm as a legitimate adaptation in its own right, with major implications for female sexual behavior and sexual evolution,"[9] others, such as Donald Symons and Stephen Jay Gould, have asserted that the clitoris is vestigial or nonadaptive and that the female orgasm serves no particular evolutionary function.

He said that the "male biologists who fretted over [the adaptionist questions] simply assumed that a deeply vaginal site, nearer the region of fertilization, would offer greater selective benefit" due to their Darwinian, summum bonum beliefs about enhanced reproductive success.

Quite the opposite; in her methods and in her writing, she advocates and demonstrates a commitment to the careful application of evolutionary theory to the study of human behavior," stated Meredith L. Chivers.

[5] By contrast, Nancy Tuana, at the 2002 conference for Canadian Society of Women in Philosophy, argues that the clitoris is unnecessary in reproduction, but that this is why it has been "historically ignored", mainly because of "a fear of pleasure.

In the study, women reported their past month's frequency of different sexual behaviors and corresponding orgasm rates and completed the Defense Style Questionnaire (DSQ-40), which is associated with various psychopathologies.

In FRAGMENT: Supposed to be an Epithalamium of Francis Ravaillac and Charlotte Cordé, Percy Bysshe Shelley, "a translator of extraordinary range and versatility",[173] wrote the phrase "No life can equal such a death."