The sexual response cycle is, essentially, a clinical version of how a human body responds during sex. By examining thousands of examples, scientists are able to carefully describe the events that happen in the lead-up, actual experience, and follow-up of the sexual act. If you truly want to know what exactly is going on when two people have sex, the physical side is all explained through the sexual response cycle:
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Sexual Desire Phase: The Sexual Desire Phase, sometimes called the libido, precedes actual physical or psychological stimulation. Certain chemicals in the body (primarily testosterone — the male sex hormone, which is also present in females) trigger these inner sexual feelings. Sexual excitement builds upon these feelings.
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Excitement Phase: The Excitement Phase arises when the genitals experience vasocongestion, which is a swelling caused by an increase in blood filling the tissues. This phase is usually generated by one or a combination of several physical, visual, or psychological stimuli, which can be caused either by oneself or a partner. Foreplay usually gets these responses started.
In men, this excitement leads to an erection. In women, this excitement leads to a swelling of the clitoris and vaginal lips, increased vaginal lubrication, increased breast size, and erection of the nipples. Other physical signs of this phase include increased heartbeat, breathing rate, and blood pressure. Arm and leg muscles may begin to tense; some people experience a “sex flush” on the upper abdomen that may spread to the chest area.
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Plateau Phase: In the Plateau Phase, certain aspects of the Excitement Phase reach a slightly higher level, with tensions building. Men exhibit two physical signs during this period: First, a few droplets of fluid are released at the head of the penis to act as a lubricant for the sperm. Second, the man’s testes enlarge and are pulled closer to the body.
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Orgasm Phase: During the Orgasm Phase, in both men and women, your body goes through a whole series of muscular contractions and spasms, including facial contortions, an increased respiratory rate and heartbeat, and a further increase in blood pressure. Your genitals also experience strong contractions.
The man undergoes the further contraction of ejaculation, which occurs in two stages: the moment of inevitability, characterized by sensations that mark the so-called point of no return, followed immediately by ejaculation.
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Resolution Phase: In this last phase, the body slowly returns to normal — the physical conditions that existed before the Excitement Stage began. This Resolution Phase is much longer for women than for men, making it the basis for afterplay.
In addition, men have the refractory period, which is the time needed after orgasm before the man can respond to more sexual stimulation and have another erection and orgasm. In young men, this period can be as short as a few minutes; the length of the refractory period grows as a man ages.
