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Orgasm (from Greek ὀργασμός ''orgasmos'' "excitement, swelling"; also sexual climax) is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic muscular contractions in the pelvic region characterized by sexual pleasure.〔See (133–135 ) for orgasm information, and (page 76 ) for G-spot and vaginal nerve ending information. 〕〔(【引用サイトリンク】 publisher=Health.discovery.com )〕 Experienced by males and females, orgasms are controlled by the involuntary or autonomic nervous system. They are often associated with other involuntary actions, including muscular spasms in multiple areas of the body, a general euphoric sensation and, frequently, body movements and vocalizations are expressed.〔 The period after orgasm (known as a refractory period) is often a relaxing experience, attributed to the release of the neurohormones oxytocin and prolactin, as well as endorphins (or "endogenous morphine"). Human orgasms usually result from physical sexual stimulation of the penis in males (typically accompanying ejaculation), and the clitoris in females.〔 Sexual stimulation can be by self-practice (masturbation) or with a sex partner (penetrative sex, non-penetrative sex, or other sexual activity). The health effects surrounding the human orgasm are diverse. There are many physiological responses during sexual activity, including a relaxed state created by prolactin, as well as changes in the central nervous system such as a temporary decrease in the metabolic activity of large parts of the cerebral cortex while there is no change or increased metabolic activity in the limbic ("bordering") areas of the brain. There is also a wide range of sexual dysfunctions, such as anorgasmia. These effects impact cultural views of orgasm, such as the beliefs that orgasm and the frequency/consistency of it are important or irrelevant for satisfaction in a sexual relationship,〔(【引用サイトリンク】publisher=iub.edu/~kinsey/resources )〕 and theories about the biological and evolutionary functions of orgasm. Orgasm in non-human animals has been studied significantly less than orgasm in humans, but research on the subject is ongoing. ==Definitions== In a clinical context, orgasm is usually defined strictly by the muscular contractions involved during sexual activity, along with the characteristic patterns of change in heart rate, blood pressure, and often respiration rate and depth.〔 This is categorized as the sudden discharge of accumulated sexual tension during the sexual response cycle, resulting in rhythmic muscular contractions in the pelvic region.〔〔〔 However, definitions of orgasm vary and there is sentiment that consensus on how to consistently classify it is absent. At least twenty-six definitions of orgasm were listed in the journal ''Clinical Psychology Review''. There is some debate whether certain types of sexual sensations should be accurately classified as orgasms, including female orgasms caused by G-spot stimulation alone, and the demonstration of extended or continuous orgasms lasting several minutes or even an hour. The question centers around the clinical definition of orgasm, but this way of viewing orgasm is merely physiological, while there are also psychological, endocrinological, and neurological definitions of orgasm.〔〔 In these and similar cases, the sensations experienced are subjective and do not necessarily involve the involuntary contractions characteristic of orgasm. However, the sensations in both sexes are extremely pleasurable and are often felt throughout the body, causing a mental state that is often described as transcendental, and with vasocongestion and associated pleasure comparable to that of a full-contractionary orgasm. For example, modern findings support distinction between ejaculation and male orgasm.〔〔 For this reason, there are views on both sides as to whether these can be accurately defined as orgasms.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「orgasm」の詳細全文を読む スポンサード リンク
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