The Sexual Response Cycle

The sexual response cycle is the phrase coined to describe the bodily responses to sexual arousal. The sexual response cycles are distinguished by myotonia (muscle tension) and vasocongestion (blood engorgement). Mytonia causes muscles spasms, facial contortion, and orgasmic shockwaves. Vasocongestion includes penile enlargement and erection as well as swelling of the vagina, nipples, testes, and even the ear lobes. The sexual response cycle is broken down into the four stages of excitement, plateau, orgasm, and resolution; these stages may be similar or different for males and females. (Nevid & Rathus, 2005)

Excitement Phase

During the excitement phase, both male and female experience genital tissue vasocongestion, mytonia (including nipple erection), and increased blood pressure and heart rate. In males, within the first three to eight seconds following stimulation, vasocongestion causes erection, elevation of testes, and tension and thickening of scrotum skin. In the female, the excitement phase may begin within the first 10 to 30 seconds following sexual stimulation, vasocongestion causes enlargement of vaginal tissue (including the area around the entrance to the vagina and the interior two thirds of the vagina) and the clitoris. The female also experiences a thickening of vaginal walls which darken in appearance, breast enlargement, flushing, and vaginal lubrication. (Nevid & Rathus, 2005)

Plateau Phase

During the plateau phase, vasocongestion and myotonia increase, as does the heart rate and blood pressure for both male and female. In the male, the penile head may increase in size and will become purple in color; the testes may grow one and a half times the pre-arousal size and will be raised in preparation for ejaculation; and pre-ejaculate semen may be released. In the female, the inner two-thirds of the vagina will fully expand while the outer third will thicken to prepare to grasp the penis, the clitoris will shorten and draw in behind the clitoral hood, and the uterus will raise and enlarge in size. (Nevid & Rathus, 2005)

Orgasm Phase