3.2.1 THE FOUR PHASES OF THE RESPONSE
As mentioned earlier, the male and female sexual responses are essentially the same. There are some marked differences, but they are not decisive. In fact, it makes sense to speak of a basic human sexual response and its male and female variations.
During sexual activity, the human body undergoes a number of physiological changes which form a definite, typical pattern. In the simplest terms, this pattern can be described as a build-up and release of tension. However, in order to gain greater insight into the processes involved, various scientists have divided the human sexual response not only into two, but three and four different phases. The following description of the female sexual response follows the division into four phases proposed by Masters and Johnson. (For the application of this model to males, see "The Male Sexual Response.")
It used to be believed that females were slower to respond to sexual stimulation than males. However, this belief is mistaken. Not only men but also women can become sexually aroused very suddenly, and some of them may experience one or more orgasms within a few minutes. As a matter of fact, there are women who reach orgasm fifteen to thirty seconds after they begin sexual intercourse. It seems, however, that during the first stages of arousal women are more easily distracted than men and depend more on continued direct physical stimulation. For this reason, many females seem to need a longer time to reach orgasm during coitus than their male partners, whose excitement is often sustained and increased by psychological factors. In general, females are less easily stimulated by mere sights and sounds, or by erotic fantasies and anticipations. On the other hand, when the average woman is able to concentrate on her preferred method of stimulation (during masturbation, for instance), she achieves orgasm just as quickly as the average man.
In females, the first and most obvious sign of sexual excitement is the lubrication of the vagina. In response to effective stimulation, the vaginal walls begin to secrete a clear fluid which soon provides a moist coating for the entire vagina in preparation for coitus. Without such lubrication, the insertion of a man's penis into a woman's vagina could be painful for both. (The corresponding first sign of sexual excitement in males is the erection of the penis. In short, as the penis becomes ready to enter the vagina, the vagina becomes ready to receive it.) With continued arousal, the inner two-thirds of the vagina increase in both length and width, creating a tenting or ballooning effect. (In its unexcited state, the vagina is a collapsed tube, i.e., its walls are touching.) At the same time, there is a vaginal color change from the usual purple-red to a deep purple that becomes even darker during the following phases.
A woman's major lips (the outer lips of the vulva) respond differently, depending on whether she has given birth to children or not. If she has not given birth, sexual excitement will cause her major lips to flatten out and expose the vaginal opening. The major lips of a woman who has given birth, on the other hand, are rather large and now grow even larger as a result of engorgement. Nevertheless, they also expose the vaginal opening. The minor lips (the inner lips of the vulva) swell considerably in all women and also change their color to a progressively deeper red. The clitoris (just as the penis) increases in size as its erectile tissue becomes filled with blood. This increase is usually most noticeable in the diameter of the clitoral shaft. The uterus also begins to swell and is pulled upward into the abdomen, thus contributing to the lengthening of the vagina mentioned above.
During sexual excitement, the nipples of the breasts become erect and maintain this erection throughout the other phases. However, since the dark area around each nipple, and, indeed the whole breast, soon also becomes engorged and swollen, the nipple erection itself gradually appears less conspicuous. Mounting sexual tension further produces voluntary and involuntary muscular contractions in various parts of the body as well as a rise in pulse rate and blood pressure.
In addition to all the above signs of growing sexual excitement, most women also show a so-called sex flush, i.e., a red rash which begins in the stomach area and then spreads to the breasts and neck. This rash lasts through the orgasmic phase.
The plateau phase is nothing more than the continuation of the excitement phase. The word "plateau" is meant to indicate that a certain even level of excitement has been reached which is then maintained for a while before orgasm occurs.
During this phase, there is only a slight increase in length and width of the inner two-thirds of the vagina. However, its outer one-third becomes congested with blood. As a result, this part of the vagina, which might have widened somewhat during the excitement phase, now narrows by about 33 percent. This congested and tightening outer third of the vagina has been named the "orgasmic platform" by Masters and Johnson.
While the major lips show no further changes during the plateau phase, the minor lips continue to darken in color, especially in women who have given birth. This marked color change is a sign that orgasm is approaching. Once a certain level of excitement has been reached, the clitoris retracts under the clitoral hood or foreskin, and thus becomes inaccessible to direct stimulation by the woman or her sexual partner. (In the past, it was not always understood that this retraction of the clitoris indicates an increase, not decrease, of sexual excitement.) The greater vestibular (Bartholin's) glands (which correspond to the bulbourethral [Cowper's] glands in the male) may secrete a small amount of fluid during the plateau phase or late in the excitement phase. Also, the uterus is pulled further upward into the abdomen and further increases in size.
The breasts also reach their greatest expansion during the plateau phase, and the sex flush, if indeed it should have occurred, may now become more intense and cover a wider area. Voluntary and involuntary muscular tension greatly increases throughout the body. The pulse rate and blood pressure rise, and breathing becomes faster.
Orgasm (Greek orgasmos; lustful excitement) is the sudden release of muscular and nervous tension at the climax of sexual excitement. The experience represents the most intense physical pleasure of which human beings are capable and is basically the same for females and males. An orgasm lasts only a few moments and is felt very much like a seizure or rather a series of convulsions which involve the whole body and soon lead to complete relaxation. In sexually mature males, orgasm is accompanied by the ejaculation of semen. Since women do not produce semen, they do not ejaculate. However, in all other respects the physiological processes are comparable in both sexes. (See also "The Male Sexual Response.")
While the experience of orgasm itself is essentially the same in men and women, the latter seem to be better equipped to have more than one orgasm within a short time. There are some rare cases of males who, particularly in their younger years, are capable of several orgasms in quick succession. However, this capacity is quite common in females.
There is one further difference: While the orgasmic pattern of males practically never varies, females may experience orgasm in a number of ways. In some women, orgasm is rather short and mild; in others, it is extended and violent. Even one and the same woman may find herself responding quite differently on different occasions. However, the basic physiological processes underlying these possible variations remain unchanged.
In females, orgasm begins with strong, rhythmic contractions of the outer one-third of the vagina, which Masters and Johnson call the orgasmic platform. These contractions, which may number from three to fifteen, first recur within less than a second, then, as they become weaker, at longer intervals. Almost at the same time, the uterus begins to contract. However, the uterine contractions are irregular. They start at the top, working their way down, not unlike the contractions during the first stage of labor. The sphincter muscles of the rectum may also contract a few times at the same intervals as the orgasmic platform. In general, there is great muscular tension, not only in the entire pelvic area, but also in other parts of the body, such as the neck, arms, hands, legs, and feet. The pulse rate and blood pressure rise slightly even beyond the level reached during the plateau phase, and breathing is very fast. The intensity of all of these physical reactions depends, of course, on the degree and duration of sexual tension. As explained earlier, during orgasm some women may also experience an "ejaculation" of "prostatic" fluid from well-developed urethral glands ("female prostate") through the urethra. (See preceding chapter under "The Vagina.")
After orgasm, the sex organs (and with them the whole body) need some time to return to their unexcited state. During this so-called resolution phase, the congestion in the outer one-third of the vagina (the orgasmic platform) disappears quickly. The major and minor lips again assume their former shape and size. The clitoris reemerges from under the clitoral hood. The uterus also shrinks back to its usual size, and, as it descends from its elevated position in the abdomen, the "tenting" or "ballooning" effect in the inner two-thirds of the vagina is eliminated. The sex flush mentioned earlier vanishes. The nipples of the breasts and the breasts themselves slowly return to their normal state. With the release of muscular tension, the pulse rate and blood pressure decrease, and breathing becomes normal again.
It should be noted at this point that, unlike men, many women do not seem to have a "refractory period," or at least it is not as obvious. In many cases continued or repeated stimulation can bring a woman to a second and third orgasm immediately following the first one. Indeed, many women are capable of having many orgasms in quick succession. Obviously, in this case, the resolution phase as described here does not begin until after the last of those orgasms.