Women and men may be more alike in their sexual response than you may have thought. Masters and Johnson found that the biological responses of males and females to sexual stimulation or their Sexual Response Cycle are similar. The term sexual response cycle decr8bes the changes that occur in the body as men and women become sexually aroused. The cycle is divided into four phases: excitement, plateau, orgasm and resolution.

The first phase of the sexual response cycle is called the excitement phase. This is characterized by engorgement of blood vessels with blood which swells the genitals and breast during sexual arousal which is called vasocongestion. In males, this causes erection of the penis, the scrotal skin thickens which makes it less baggy and the testes increase in size.

In females, the excitement phase is characterized by the vagina getting lubricated. In females, vasocongestion causes the inner two-thirds of the vagina to expand and the vagina walls to thicken and turn a deeper color and the breast enlarges.

The excitement phase for both males and females may cause the nipples and the earlobes swell with blood, the skin may become rosy. The heart rate and the blood pressure increases. Also, myotonia occurs which causes facial grimaces, spasms in the hands and feet and then the spasms of orgasm.

The next stage, the plateau phase, sexual arousal remains somewhat stable. In males there is some increase in the circumference of the head of the penis, which also takes on a purplish hue. The testes are now elevated into the position for ejaculation. A man’s penis may become one and a half time their unaroused sized. Droplets of semen may be released from the penis opening before ejaculation happens.
In women, the plateau phase causes the outer part of the vagina to swell, contracting the vaginal opening in preparation for grasping the penis. The inner part of the vagina expands further and the clitoris withdraws beneath the clitoral hood and shortens. The uterus elevates and increases in size.

In the plateau stage for both male and female, breathing becomes rapid, like panting, the heart rate increases to 100 to 160 beats per minute and the blood pressure continues to rise.

The orgasmic phase for males consist of two stages of muscular contractions. The first stage the semen collects at the base of the penis. When this is happening the sphincter prevents urine from mixing with semen. In the second stage the muscle contractions propel the ejaculate out of the body. Sensations of pleasure are related to the strength of the contractions and the amount of seminal fluid present. The first three to four contractions are generally most intense and a man can have five contractions every four seconds. Another tow to four contractions occurs at a somewhat slower pace and this process can vary from man to man.

In the orgasmic phase for females orgasm is manifested by three to 15 contractions of the pelvic muscles that surround the vaginal barrel. The contractions at first are at the same intervals as in males and as in males they produce release of the sexual tension, and then weaker and slower contractions follow.

In the orgasmic stage for both male and female, blood pressure and the heart rate increases even move reaching its peak of up to 180 beats per minute and muscle spasms occur throughout the body. Breathing is also increased.

In the resolution phase for both males and females, the body is returning to its unaroused state. Both male and female may feel relaxed and satisfied.

In males, blood is released from the engorged areas so that the erection disappears and the testes return to their normal size. Men enter a refractory period during which they cannot experience another orgasm or ejaculate. The refractory period for adolescent may last minutes, however, in men age 50 and over it may last from several minutes to a day.

In females, the blood is also release from the engorged areas. The nipples return to their normal size, blood pressure, heart rate and breathing return to their normal levels. Women do not go through a refractory period and because of this they can become rearoused rather quickly to the point of having multiple orgasms if they desire and receive continued sexual stimulation.

Sexual dysfunctions are the persistent recurring problems in becoming sexual interest, arousal or reaching orgasm. Millions of Americans experience sexual dysfunctions but many people are reluctant to admit to sexual problems. More women reported problems of painful sex, having trouble lubricating, lack of pleasure, inability to reach orgasm and lack of interest in sex. More men reported reaching orgasm too early, unable to keep an erection, and being anxious about their performance.

Orgasmic disorder, the man or woman, although sexually excited is persistently delayed in reaching orgasm or does not reach orgasm at all. This disorder is more common in woman than in men. In some cases, an individual can reach orgasm without difficulty while engaging in sexual relations with one partner but not with another.

Premature ejaculation is when the male persistently ejaculates with minimal sexual stimulation and too rapidly to p0ermit his partner or himself to fully enjoy sexual relations.

Many causes of sexual dysfunctions are caused by biological problems. Lack of desire can be due to diabetes or deficient levels of testosterone. Testosterone is the hormone that plays a key role in activating sexual drive in both men and women. Fatigue can reduce sexual desire and inhibit orgasm. Depressant such as alcohol, narcotics and tranquilizers can also impair sexual response. Lack of sexual drive or interest is often connected with mental disease, such as depression.

Health problems can affect orgasm in both male and females. These problems include coronary heart disease, diabetes mellitus, multiple sclerosis, spinal-cord injuries and use of some therapeutic drugs, such as drugs used to treat hypertension and mental health problems.
Organic causes of erectile disorder often involve medical problems that affect the flow of blood to and through the penis or damage to nerves involved in erection. For example, the arteries leading to the penis become clogged or narrowed. Erectile dysfunction was also connected with large waist, physical inactivity and drinking too much alcohol. The common condition among these men may be high cholesterol levels. Age is also a factor with obtaining or keeping an erection. The older the man is the harder it is to maintain.

Female sexual arousal disorder may also have physical causes. For example, diabetes mellitus may lead to diminished sexual excitement in women because of the degeneration of the nerves servicing the clitoris and the blood vessel damage it causes. Reduced estrogen production, because of aging, can also result in vaginal dryness.

Female sexual arousal disorder more commonly has psychological causes. Some women harbor deep-seated anger and resentment toward their partners and find it difficult to turn off these feelings when they go to bed. In other cases sexual trauma is the cause of arousal disorders such as rape. Survivors of sexual abuse often find it difficult to respond sexually to their partners. Childhood sexual abuse is especially common to respond arousal disorder. Feelings of helplessness, anger or even flashbacks of the abuse may surface when the woman begins sexual activity, dam0pening her ability to become aroused.

Resources:

Chapter 13 of Psychology and the Challenges of Life: Adjustment in the New Millennium