The Excitement Phase

The very first sign of sexual arousal in men, of course, is erection of the penis – a marked increase in its size, and a rise in its angle of protrusion from the body.

Erection may be triggered by stimulation of the penis itself or by a sexually stimulating sight or by an erotic train of thought.

It occurs within a few seconds, regardless of the nature of the stimulation.

During erection a small penis may double or more than double in length. In a large penis, the lengthening is less marked. Thus there is less variation in length among erect than among flaccid penises.

Erection is due to the engorgement of the penis with blood; indeed, as we shall see, many of the most important sexual responses occurring in both men and women are the direct result of this kind of engorgement.

More blood flows into an organ than flows out of it; the result is engorgement or vasocongestion.

This change in blood supply, occurring not only in the penis but also in other male and female organs, is the primary reflex action to sexual stimuli.

The secondary reaction is a contraction of various muscle fibres, muscles, and groups of muscles.

The first sign of sexual response in women may seem to be different from either engorgement or muscular contraction; it is the moistening of the vagina with a lubricating fluid.

This lubrication occurs quite promptly – within ten to thirty seconds of the onset of sexual stimulation.

The lubrication appears with equal promptness whether the stimulus is direct stimulation of a woman’s genital region, or of her breasts, or is an erotic train of thought.

Bartholin’s glands do sometimes contribute a few drops of a lubricating fluid to the vaginal entrance – but only late in the response cycle, following prolonged sexual activity and following copious lubrication of the vagina from a “sweating reaction” occurring on the walls of the vagina. 

As sexual excitation continues, these drops coalesce to provide a lubricating film, readying the vagina for the entrance of the penis.

The increase in the size of the penis and the “sweating” of the vaginal walls may seem completely different responses, but they may have a common cause.

More blood enters the tissues around the vagina than can leave, producing vasocongestion.

Both the walls of the smaller blood vessels and the walls of the vagina are “semi-permeable membranes”; they hold fluids back under some conditions but let them seep through under others.

The droplets of moisture that appear on the surface of the vagina during sexual excitation, it seems probable, have seeped out of the congested blood vessels.

Thus engorgement with blood is the cause of both the male erection and vaginal lubrication.

The appearance of vaginal lubrication very early in the female response cycle is a point that deserves attention.

Some sex manuals state, and some men no doubt believe, that the appearance of vaginal lubrication signals a woman’s readiness to engage in sexual intercourse.

This is true in a sense. The woman is beginning to respond, and lubrication does ready the vagina for the entrance of the penis.

Entry prior to the appearance of adequate lubrication can be difficult and uncomfortable, or even painful.

But, as we shall see, many more changes must follow before a woman is fully aroused erotically and emotionally ready for sexual penetration and orgasm. Important changes occur, for example, in the clitoris.

This organ is located just above the entrance to the vagina. Like the penis, it is a shaft with a bulb or “glans” at the tip.

Both the shaft and the glans vary in size from woman to woman. The size and location of the clitoris bear no relation whatever to a woman’s sexual responsiveness or her ability to achieve orgasm.

The glans of the clitoris is packed with sensitive nerve endings.

The stimulation of the glans thus contributes greatly to heightening a woman’s sexual response. Direct contact with the clitoris is not necessary in order to stimulate it.

The glans is covered with a hood or prepuce; and this hood is attached to the inner lips (minor labia) of the vagina.

Thus during ordinary sexual intercourse the rhythmic thrusting of the penis through the inner lips produces a rhythmic friction between the clitoral hood and the glans.

In addition, the clitoris is responsive to purely psychological stimuli, such as an erotic train of thought. In the laboratory, changes in the clitoris can be directly observed during purely psychological stimulation, even though the clitoris and other genital organs remain untouched.

Changes in the clitoris can also be observed following stimulation of the breasts.

The first of these changes is the swelling of the clitoral glans. In some women on some occasions, the glans may actually double in size.

In other women, the swelling may be so slight that it can only be observed with the help of a device which enlarges the object viewed by forty diameters or so.

The amount of swelling, however like the size and location of the clitoris – is not related to either sexual responsiveness or to ability to achieve orgasm.

The swelling of the glans of the clitoris, like the swelling of the glans of the penis, is no doubt the result of engorgement of the blood vessels inside it.

Simultaneously with the swelling of the clitoral glans, the clitoral shaft also increases in diameter.

The time at which these changes occur depends upon the nature of the sexual stimulation to which the woman is responding.

If her mons veneris – that is, the area surrounding her clitoris – is being stimulated directly, the engorgement of the clitoral glans and shaft may occur quite promptly after the appearance of vaginal lubrication.

If the stimulus is breast manipulation or an erotic train of thought, the clitoral response generally takes somewhat longer.

A series of changes also occurs in the female breasts during this initial or “excitement phase” of erotic response. The first of these changes is an erection of the nipples. This erection is caused by contraction of muscle fibres.

Often one nipple erects first and the other follows immediately, or after a considerable delay.

In addition, the nipples increase both in length and in diameter as a result of blood-vessel engorgement similar to the engorgement of the penis and clitoris.

The pattern of veins ordinarily visible on the surface of the breasts becomes more distinct, and veins previously invisible may make their appearance during this engorgement process.

The female breasts also increase in size late in the excitement phase; this is a sign of heightened sexual tension preliminary to the transition to the next phase of sexual response.

The swelling of the breasts is more noticeable in women who have not breast-fed babies. Late in the excitement phase, too, the areolas – that is, the rings of darker skin surrounding the nipples – become engorged and swell.

Response of the male breast is less consistent.

However, at least partial nipple erection was observed in three-fifths of the men participating in studies. It generally occurred late in the excitement phase.

The outer lips (major labia) at the entrance to the vagina respond in several ways during the excitement phase. In an unexcited state, they generally meet in the mid-line of the vagina, protecting the inner lips and the other structures within.

During excitation they open a bit, and may be displaced a bit upward, toward the clitoris.

These changes are likely to occur quite late in the excitement phase. In women who have not had a baby, the outer lips also thin out and flatten themselves against the surrounding tissues.

In women who have had several babies, and especially in those who have developed varicose veins in their outer lips, the outer lips become noticeably distended and engorged with blood instead of flattening.

In extreme cases there may be a two-fold or even three-fold increase in size, so that the outer lips come to resemble a sort of curtain surrounding the vaginal opening. In these cases, too, the lips tend to open outward toward the sides as erotic tension increases, so that they do not interfere with the entry of the penis.

The inner lips (minor labia) also tend to swell during the excitement phase; indeed, it may be the swelling of the inner lips that produces the opening-out of the outer lips, an invitation for the entry of the penis.

The vagina, too, responds. It can be thought of as a cylinder or “barrel”, which remains in a collapsed state in the absence of erotic stimulation. Studies have established that the outer third of this barrel reacts in one way and the inner two-thirds in a very different way during the successive phases of sexual response.

As sexual tension mounts during the excitement phase, the inner two-thirds of the vaginal barrel begins to expand, and then relaxes again. Slowly the demand to expand overcomes the tendency to relax, and the clinically distended vaginal barrel of the sexually responding woman is established.

The cervix and uterus are pulled up and back at about this time, producing a “tenting” of the vaginal walls surrounding the cervix. The net result of these and other changes is a dramatic “ballooning” of the inner two-thirds of the vagina.

I am struck as  I write this by the somewhat detached almost “magician-like perspective” that this scientific approach lends to something as sensitive and delightful as lovemaking. We must never forget the fact that at the end of the day two people in love may be swept along by their feelings and emotions rather than the mechanics of sex!

The diameter at the widest point of the ballooning may be three times the diameter of the erotically unstimulated vagina; and the total length of the vaginal barrel may be increased as much as a full inch. (The swelling of the inner lips of the vagina also contributes to this lengthening.)

The ballooning is accompanied by a change in the appearance of the vaginal walls; the wrinkles, or “rugae”, are smoothed out and the colour of the walls changes from a normal purplish red to a darker purple, indicating engorgement of the surrounding blood vessels.

In addition to these responses in the sex organs and breasts, there are many indications that the entire body, in both women and men, is participating in this gradual process of sexual arousal.

In both women and men, the voluntary muscles tend to tense up, and there may also be some contraction of groups of involuntary muscles.

The pulse rate speeds up, and the blood pressure rises. Most remarkable of all, perhaps, a “sex flush” often appears upon the skin.

This sex flush appears first on the upper portion of the abdomen, then spreads up over the breasts. It often takes the form of a measles-like rash. The time of appearance is variable. In most men, and in some women, it does not appear until later in the response cycle, and in some it does not appear at all.

But about three-quarters of the women, and one-quarter of the men, exhibit the sex flush prior to orgasm on at least some occasions. So if a man wishes to know if he has given a woman an orgasm, this is not a reliable indicator.

Changes are also noted in the male testes and scrotum during this first phase of sexual response.

There is a tensing and thickening of the skin of the scrotum; and the whole scrotal sac is elevated and flattened toward the body.

The spermatic cords, by which the testes are suspended, shorten, so that the testes are pulled farther up in the sac.

Just as the nipple of one breast often becomes erect before the other, so one of the testes often rises before the other.