His sexual response

orgasmic phase

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Orgasm, the release of sexual tension, involves many bodily changes. While no one is really sure how the nervous system or biochemical systems trigger an orgasm, what is known is that physical and psychological factors are important. Interestingly, physical stimulation of the genitals is not required for an orgasm; some people can have orgasms simply by thinking erotic thoughts.

The feelings of orgasm are usually centered within the penis. The onset of orgasm is accompanied by rhythmic contractions of the seminal vesicles, vas deferens, prostate gland, and ejaculatory ducts. These contractions push the semen into the urethra just prior to ejaculation. 

At the actual point of ejaculation, contractions occur along the entire length of the urethra that force the semen out of the body. The first few contractions are the strongest and occur less than one second apart. These powerful contractions are followed by weaker ones that may last for several more seconds. Contractions of the anal sphincter and of the pelvic floor also occur during this phase.

Unlike women, men have something known as the "point of imminence." A few seconds prior to ejaculation a man knows he is going to have an orgasm no matter what. Indeed, one research team fired off a starter-pistol at this "point of imminence" while observing a participant who, despite being extremely startled and distracted, proceeded on course.

next phase:
resolution