Orgasm: Encyclopedia II - Orgasm - Human female orgasm

Orgasm - Human female orgasm

In a human female orgasm, orgasm is preceded by moistening of the vaginal walls, and an enlargement of the clitoris due to increased blood flow trapped in the clitoris's spongy tissue. Some women exhibit a sex flush; a reddening of the skin over much of the body due to increased blood flow to the skin. As a woman comes closer to having orgasm, the clitoris moves inward under the clitoral hood, and the labia minora (minor lips) becomes darker. As orgasm becomes imminent, the vagina decreases in size by about 30% and also becomes congested from engorged soft tissue. The uterus then experiences muscular contractions. A woman experiences full orgasm when her uterus, vagina and pelvic muscles undergo a series of rhythmic contractions. The majority of women consider these contractions to be very pleasurable.

After the orgasm is over, the clitoris re-emerges from under the clitoral hood, and returns to its normal size in less than 10 minutes. Unlike men, women either do not have a refractory period or have a very short one, and thus can experience a second orgasm soon after the first; some women can even follow this with a third, or even fourth orgasm; this is known as having multiple orgasms. After the initial orgasm, subsequent climaxes may be stronger or more pleasurable as the stimulation accumulates. Research shows that about 13% of women experience multiple orgasms; a larger number may be able to experience this with the proper stimulation (such as a vibrator) and frame of mind. However, some women's clitorises are too sensitive after orgasm, making additional stimulation painful; they are probably not able to experience multiple clitoral orgasms.

Orgasm - The evolutionary purpose of orgasms

Some evolutionary biologists believe that female orgasms have a distinct purpose, such as increasing intimacy with a male partner in order to ensure the survival of the pair bond. Others have theorized that they increase fertility by enhancing sperm retention. The British biologists Baker and Bellis have suggested that the female orgasm may have an "upsuck" action, retaining favourable sperm and making conception more likely[3]. Other biologists, such as Stephen Jay Gould, suggest the female orgasm is analogous to the male nipple, an evolutionary holdover which, though associated with pleasure in the context of sexual behaviour, has no specific identified biological function.

The clitoris is homologous to the penis, that is, the penis and clitoris develop from the same embryonic structure. It has been claimed by some researchers, such as Stephen Jay Gould that the clitoris is vestigial in the female, and that female orgasm serves no particular evolutionary function. Proponents of this theory, such as Dr. Elisabeth Lloyd, point to the relative difficulty of achieving female orgasm through vaginal sex, and limited evidence for increased fertility after orgasm. Feminists such as Natalie Angier have criticized that this theory understates the psychosocial value of female orgasm. Catherine Blackledge in The Story of V has criticized the theory from a more scientific standpoint, citing studies that indicate a possible connection between orgasm and successful conception.

35% of women report never or seldom achieving orgasm during intercourse, and only 10% always orgasm. This variation in ability to orgasm is generally thought to be psycho-social, but has been found to be between 34-45% genetic, according to a 2005 twin study published in Biology Letters, a Royal Society journal.^[4][5][6]

The researchers stated that the fact that it is heritable suggests that evolution has a role. They suggested this difficulty in achieving orgasm might have evolved because it helped females select males who were the most powerful and thoughtful, who would be the most likely to hang around as a long-term partner and be a better bet for bringing up offspring. In this theory, women who orgasm easily may have been satisfied with mates who were less skilled. While in certain cultures it has been posited that women who are more orgasmic may be more promiscuous, there has to date been no confirmation of this in a scientific study.

Orgasm - Vaginal versus clitoral orgasms

A distinction is sometimes made between clitoral and vaginal orgasms in women. An orgasm that results from combined clitoral and vaginal stimulation is called a blended orgasm. Many doctors and feminist advocates have claimed that vaginal orgasms do not exist, and that female orgasms are obtained only from clitoral arousal. Recent discoveries about the size of the clitoris — it extends inside the body, around the vagina — would seem to support this theory. On the other hand, other sources argue that vaginal orgasms are dominant or more "mature".

This latter viewpoint was first promulgated by Sigmund Freud. In 1905, Freud argued that clitoral orgasm was an adolescent phenomenon, and upon reaching puberty the proper response of mature women changes to vaginal orgasms. [7] While Freud did not provide evidence supporting this basic assumption, the consequences of the theory were greatly elaborated thereafter.

In 1966, Masters and Johnson published pivotal research into the phases of sexual stimulation. Their work included women as well as men, and unlike Kinsey previously (in 1948 and 1953), set out to determine the physiological stages leading up to and following orgasm. [8] One of the results was the promotion of the idea that vaginal and clitoral orgasms follow the same stages of physical response. Additionally, Masters and Johnson argued that clitoral stimulation is the primary source of orgasms.

This standpoint has been adopted by feminist advocates, to the extent that some hold that the vaginal orgasm was a mirage, created by men for their convenience. Certainly many women can only experience orgasm with clitoral stimulation, either alone or in addition to vaginal stimulation, while (less commonly) other women can only experience orgasm with vaginal stimulation. The clitoral-only orgasm school of thought became an article of faith in some feminist circles. Alternatively, some feminists feel the clitoral orgasm robs females of the source of their womanhood.

A new understanding of vaginal orgasm has been emerging since the 1980s. Many women report that some form of vaginal stimulation is essential to subjectively experience a complete orgasm, in addition to or instead of external (clitoral) stimulation. Recent anatomical research has pointed towards a connection between intravaginal tissues and the clitoris. It has been shown that these tissues have connecting nerves. This, combined with the anatomical evidence that the internal part of the clitoris is a much larger organ than previously thought could also explain credible reports of orgasms in women who have undergone clitoridectomy as part of so-called female circumcision.

In some cases it is possible for women to orgasm through stimulation of secondary sexual organs (e.g. breasts), and in very rare cases, without any direct stimulation to the genitalia or the other specific erogenous zones, but instead stimulation of the non-specific zones (e.g. neck).

Some women experience orgasm while giving birth. In addition, orgasm can be spontaneous, seeming to happen with no direct stimulation. Occasionally, orgasm can occur during sexual dreams.

Adapted from the Wikipedia article "Human female orgasm", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki