Proper sexual functioning in men and women depends on the
sexual response cycle, which consists of an anticipatory
mental set (sexual motive state or state of desire), effective
vasocongestive arousal (erection in men; swelling and
lubrication in women), orgasm, and resolution. In men, the
sensation of orgasm includes emission followed by ejaculation.
Emission, mediated by contractions of the prostate, seminal
vesicles, and urethra, produces a sensation of ejaculatory
inevitability. In women, orgasm is accompanied by
contractions (not always subjectively experienced as such) of
the muscles of the outer third of the vagina. In both sexes,
generalized muscular tension, perineal contractions, and
involuntary pelvic thrusting (every 0.8 sec) usually occur.
Orgasm is followed by resolution--a sense of general pleasure,
well-being, and muscular relaxation. During this phase, men are
physiologically refractory to erection and orgasm for a variable
period of time, but women may be able to respond to additional
stimulation almost immediately.