Chapter 6 Sexual Arousal and Response

The Brain and Sexual Arousal Cerebral cortex (mental events) Reasoning, language, and imagination Limbic system and sexual behavior Hypothalamus Neurotransmitters Dopamine facilitates sexual arousal Serotonin inhibits sexual arousal

The Limbic System and Sexual Behavior Caption: The limbic system, a region of the brain associated with emotion and motivation, is important in human sexual function. Key structures, shaded in color, include the cingulate gyrus, portions of the hypothalamus, amygdala, and the hippocampus.

The Senses and Sexual Arousal All sensory systems can contribute to arousal Touch is the dominant “sexual sense” Primary erogenous zones Secondary erogenous zones Vision usually next in dominance Visual stimuli Men self-report higher arousal than women Women and men have similar physiological responses It has been said that women enjoy hugging and touching more than genital sex, whereas men have little interest in the “preliminaries,” preferring to “get down to the real thing.” Do you believe this statement reflects a genuine difference between the sexes? If so, is it learned or biologically determined?

Other Senses and Sexual Arousal Smell may arouse or offend Pheromones Taste plays a minor role Hearing plays a variable role

Aphrodisiacs Substances believed to arouse sexual desire or increase capacity for sexual activity Food Drugs and alcohol Yohimbine No clear evidence of genuine aphrodisiac qualities Role of expectations Assume that research eventually reveals that yohimbine or some other substance has genuine aphrodisiac qualities. What possible benefits might be associated with its use? What possible abuses might arise? Would you consider using an aphrodisiac? If so, under what conditions?

Anaphrodisiacs Inhibits sexual behavior Drugs (e.g. opiates, tranquilizers) Antihypertensives, antidepressants & antipsychotics Birth control pills Nicotine Constricts blood flow Possibly reduces circulating testosterone

The Role of Hormones in Sexual Behavior Steroid hormones Androgens (including testosterone) Produced by testes, adrenal glands, and ovaries Estrogens Produced by ovaries and testes Women and men produce both types Neuropeptide hormones Oxytocin

Sex Hormones in Male Sexual Behavior Testosterone Linked to sexual desire and genital sensitivity Castration leads to reduced sexual desire Antiandrogen drugs Hypogonadism

Sex Hormones in Female Sexual Behavior Estrogens Overall link between estrogen and female sexual behavior is unclear Estrogen Therapy (ET) Testosterone Role as major libido hormone in females

How Much Testosterone Is Necessary? Two forms of testosterone (free and bound) Free testosterone linked to libido Although women have less free testosterone, their cells are more sensitive to it than men’s Too much testosterone is linked to adverse effects Testosterone levels decrease with age Fairly rapid decrease for women at menopause; more gradual decline for men Testosterone Replacement Therapy

Oxytocin and Sexual Behavior Secreted during cuddling and physical intimacy Increased skin sensitivity High levels associated with orgasmic release for women and men For women, stimulates contractions of uterine wall during orgasm

Sexual Response Caption: Kaplan’s three-stage model of the sexual response cycle. This model is distinguished by its identification of desire as a prelude to sexual response. Source: Kaplan 1979.

Sexual Response Master’s and Johnson’s Four Phases Excitement Plateau Orgasm Resolution

Sexual Response Master’s and Johnson’s Four Phase Model Phases of physiological responses Two basic physiological processes Vasocongestion Myotonia

Sexual Response Cycle Caption: Major physiological changes during each of the four phases of the sexual response cycle

Female Sexual Response Caption: Major changes in female sexual anatomy during the sexual response cycle.

Male Sexual Response Caption: Major changes in male sexual anatomy during the sexual response cycle.

Orgasm Shortest phase of sexual response cycle Men and women’s subjective descriptions of orgasm are similar Most female orgasms result from stimulation of the clitoris Grafenberg spot Area on lower front wall of vagina Sensitive to pressure Sometimes results in “ejaculation” Do you believe that men and women differ in the importance they attach to experiencing orgasm during sexual sharing? Why or why not?

Sex Differences in Sexual Response Greater variability in female response Male refractory period Women can experience multiple orgasms

Locating the Grafenberg Spot Caption: Locating the Grafenberg spot. Usually two fingers are used, and it is often necessary to press deeply into the anterior wall of the vagina to reach the spot.

Aging & Sexual Response Cycle Older women Response cycle continues, but with decreased intensity Excitement: Vaginal lubrication begins more slowly, reduced amount Plateau: decreased vagina flexibility Orgasm: number of uterine contractions decrease Resolution: occurs more rapidly

Aging and the Sexual Response Cycle Older men Response cycle continues, with changes in intensity and duration of response Excitement: lengthened time to erection Plateau: able to sustain plateau phase longer Orgasm: reduced muscular contractions and force of ejaculation Resolution: occurs more rapidly refractory period lengthens

Age-Related Changes in the Sexual Response Cycle Caption: Common changes in the sexual response cycle of older women and men.