Chapter 6 Sexual Arousal and Response

1. Chapter 6Sexual Arousal and Response

2. Hormones • Steroid hormones • Commonly referred to as “male sex hormones” and “female sex hormones,” although both sexes produce both types of hormones. • Testosterone: the major androgen, or male sex hormone • Produced in the testes (men), adrenal glands (men and women), & ovaries (women). • Men typically produce 20-40X more testosterone than women. • Estrogen: the major female sex hormones • produced by ovaries & testes. • Testes produce much smaller quantities of estrogens than ovaries. • Neuropeptide hormones • Oxytocin--often called the “love hormone;” seems to influence erotic and emotional attraction to one another. • Produced in the brain by the hypothalamus.

3. Hormones in male sexual behavior • Testosterone linked to male sexual desire (libido) • Less linked to functioning; a man w/low testosterone level can be fully capable of erection and orgasm but might have little interest in sex. • Evidence 1) Research on men who have undergone castration shows significant reduction in sexual desire and activity. 2) Androgen-blocking drugs (antiandrogens) • Have been used to try and treat sex offenders, and are used to treat some medical conditions, such as prostate cancer. • Depo-provera (medroxyprogesterone acetate, MPA) has been shown to reduce sexual desire and activity in men and women. 3) Hypogonadism: endocrine disorder causing testosterone deficiency in males; also causes major reduction in sexual desire that can be treated with testosterone replacement.

4. Hormones in female sexual behavior • Testosterone linked to female sexual desire (libido) • Evidence 1) Testosterone-replacement therapy enhances sexual desire and arousal in post-menopausal women and other women with low levels of testosterone 2) In women with normal testosterone levels, supplemental testosterone caused a significant increase in genital responsiveness within hours. 3) Women with a history of low sex drive and inhibited arousal positively responded to testosterone administration. 4) Comparisons of women w/history of healthy sex drive and women w/history of low libido showed that women in the low-libido group had lower testosterone levels.

5. Hormones in female sexual behavior, (cont.) • Estrogens: role in female sexual behavior is still unclear. • Contribute to general sense of well-being • Help maintain thickness & elasticity of vaginal lining • Contribute to vaginal lubrication • However, there are contradictory findings about whether administration of estrogen increases or decreases libido in women.

6. How much testosterone is necessary for normal sexual functioning? • Levels of free testosterone are much lower in women than men. • This does not mean that women have lower or weaker sex drives. • Rather, women’s body cells are more sensitive to testosterone than a man’s body cells are. • Testosterone levels decline w/age in both sexes.

7. Testosterone replacement therapy • Use of testosterone supplements to treat a deficiency in testosterone. • Relatively common to treat sexual difficulties in men. • Women have a harder time receiving TRT, although testosterone deficiency is a fairly common experience during menopause. • There are some negative side effects, and long-term effects of TRT aren’t yet known. • Can stimulate growth of prostate cancer cells, if present. • Some concerns about cardiovascular problems in men. • Little research done on TRT in women. • More long-term studies are needed.

8. Oxytocin in male & female sexual behavior • Oxytocin: a neuropeptide (a short string of 9 amino acids produced in the hypothalamus in both sexes). • Stimulates release of milk during breast-feeding; thought to facilitate mother-child bonding • Released during physical intimacy/touch • Increases skin sensitivity to touch • High levels are associated w/orgasm • Levels remain high after orgasm; thought to contribute to emotional and erotic bonding of sexual partners • Research suggests oxytocin is important for facilitating social attachments and development of feelings of love. • Stress lowers oxytocin secretion.

9. Funny ad . . . oxytocin spray!

10. The brain and sexual arousal • Sexual arousal can occur w/o any sensory stimulation, through thoughts and fantasy alone. • Stimuli that people find arousing is greatly influenced by cultural conditioning. • Features that are considered attractive vary from one culture to another. • In many cultures, bare female breasts are not viewed as erotic stimuli, as they are in the U.S. • Foreplay leading to arousal varies considerably in different cultures. • Ex: in a survey of 190 cultures, mouth kissing was only practiced in 21.

11. Anatomical regions of the brain involved in sexual arousal & response cerebral cortex: thinking center of the brain Limbic system: associated w/emotion & motivation; also includes the “pleasure center”

12. Limbic system • Associated with emotion, motivation, and memory • Includes several brain structures • Hypothalamus, hippocampus, amygdala, cingulate gyrus • 1950s study: rats implanted w/electrodes in regions of limbic system that could be activated by a lever. • Rats pressed lever over and over, in preference to eating or drinking, eventually dying of exhaustion. • Limbic stimulation in people (done for therapeutic purposes) : patients reported intense sexual pleasure. • Damage to certain parts of the hypothalamus seems to dramatically reduce sexual behavior of both males and females in several species.

13. Neurotransmitters and sexual arousal • Dopamine • Released in the “pleasure center” of the limbic system. • Facilitates sexual arousal and response. • Testosterone stimulates dopamine release in both males and females. • Oxytocin(already discussed) • Serotonin • Inhibits sexual activity • inhibits release of dopamine. • Antidepressants called SSRIs increase serotonin levels in the brain--side effects often include decreased libido and diminished sexual response. • (selective serotonin reuptake inhibitors)

14. Sexual arousal: the role of the senses • Touch is the dominant "sexual sense” • Primary erogenous zones: areas of the body that contain dense concentrations of nerve endings. • Includes genitals, buttocks, anus, perineum, breasts, inner thighs, armpits, navel, neck, ear lobes, mouth. • Varies from one person to another. • Secondary erogenous zones: areas of the body that have become erotically sensitive through learning and experience. • Virtually any other region of the body--depends on personal erotic experiences.

15. Sexual arousal: the role of the senses • Vision: usually next important sense in arousal. • Early research supported the idea that males are more aroused by visual stimuli than females. • Reflects many social influences: • Was considered culturally inappropriate for women to view pornography. • Most pornography was made to appeal exclusively to men; some women found themes/ideas offensive. • Today, pornography and erotica is available that appeals to many women. • Studies using physiological recording devices while subjects viewed pornography showed equal physiological signs of arousal in women and men. • When arousal was assessed by self-reporting, women are less inclined to report being sexually aroused by visual erotica.

16. Sexual arousal: the role of the senses • Smell: highly influenced by a person’s sexual history and social conditioning. • In some cultures, the smell of genital secretions are considered a sexual stimulant. • Use as a ‘perfume’ by some women in Europe. • U.S.: near obsession w/masking any natural body odor • Difficult to study effect of natural odors on desire when they are so heavily masked by frequent bathing, deodorants, perfumes, and antiperspirants. • Even so, many report being aroused by the smell of their partner, or by people to whom they are attracted. • Pheromones: odors produced by the body that relate to reproductive functions (e.g. fertility). • Very important in sexual response and arousal in many animals. • Research still not clear on how important they are in humans.

17. Sexual arousal: the role of the senses • Taste: seems to play a minor role in arousal. • Hearing: highly variable. • Some people find words, erotic conversation, moans, etc. to be very arousing • Others prefer more silent sex. • Different people receive different cultural messages about whether it is “okay” to talk or make noise during sex.

18. Aphrodisiacs • Definition: substances that allegedly arouse sexual desire and increase the capacity for sexual activity. • Foods: • Many that resemble a penis: bananas, asparagus, cucumbers, ground-up horns of animals such as rhinoceros and reindeer (origin of the term horny) • Drugs: (see table) • Alcohol, amphetamines, barbiturates, cocaine, LSD, marijuana, amyl nitrite, L-dopa • Not one actually qualifies as a sexual stimulant • Some lower inhibitions, some can hinder the ability to think clearly and make conscious decisions. • Some can have dangerous side effects. Almost none of these substances actually work!

19. Table 6.2List of alleged aphrodisiacs

20. Aphrodisiacs, (cont): yohimbine • Crystalline alkaloid derived from the bark of the yohimbe tree that grows in West Africa. • Aphrodisiac effects: • In rats, yohimbine extracts induced sexual arousal and activity • Positively affected sexual desire and performance in men w/erectile disorders • Increased sexual arousal in postmenopausal women who reported below-normal levels of sexual desire. • Concerns: • However, side effects are common, such as heart palpitations, sweating, anxiety, nausea, insomnia (like a stimulant). The appropriate dose for each person is difficult to determine. • Can’t be taken by anyone w/medical problems such as heart problems, high b.p., liver problems, diabetes, or anyone taking a number of different medications.

21. Anaphrodisiacs • Definition: substances that inhibit sexual behavior • Birth control pills (progesterone-containing) • Reduce sexual desire by lowering testosterone levels • Opiates, tranquilizers, sedatives • Reduce sexual interest, activity, and function • Nicotine • Reduces sexual interest and function by constricting blood vessels and by reducing blood testosterone levels. • Blood pressure medicine, drugs that treat heart disease • Inhibit erection and ejaculation, reduce orgasm intensity, reduce sexual interest • Antidepressants • Decreased desire, erectile disorder, delayed or absent orgasm • Anticonvulsant and antipsychotic drugs

22. Models of sexual response:Masters & Johnson four-phase model  excitement  plateau  orgasm  resolution Female sexual response cycle 3 patterns identified Male sexual response cycle 1 pattern identified

23. 6-A Discussion question: Do you believe that men and women differ in the importance they attach to experiencing orgasm during sexual sharing? Why or why not?

24. Masters & Johnson four-phase model of sexual response:  excitement  plateau  orgasm  resolution • Remember: • There’s lots of individual variation. • Model focuses only on physiology, not the entire personal experience of sexual response. • Too-literal interpretation of the plateau stage • Still a lot happening, even though it’s described as a “leveling-off” • NOTE: Kaplan has Desire as first phase

25. Two fundamental physiological responses to effective sexual stimulation • Vasocongestion: engorgement of blood vessels in particular body parts in response to sexual arousal. • Myotonia: muscle tension

26. Masters & Johnson's four phases • Excitement • Plateau • Orgasm • Resolution Let’s examine the changes that occur in the internal & external anatomy of men & women at each stage…

27. Changes in external & internal male anatomy during sexual response Excitement phase: • engorgement of penis (cavernous and spongy bodies) and testes (vasocongestion) • increase in muscle tension • increased heart rate and blood pressure

28. Changes in external & internal male anatomy during sexual response Plateau phase: • engorgement and elevation of testes increases. • further increase in muscle tension, heart rate and b.p. • Cowper’s gland secretions may occur.

29. Changes in external & internal male anatomy during sexual response Emission phase of orgasm: • contractions of internal structures • both internal and external urethral sphincters contract • result: seminal fluid pools in urethral bulb (see chapter 5)

30. Changes in external & internal male anatomy during sexual response Expulsion phase of orgasm: • contractions of muscles at base of penis and in penile urethra • external urethral sphincter relaxes • result: expulsion of semen (see chapter 5)

31. Changes in external & internal male anatomy during sexual response Resolution phase: • sexual anatomy returns to the nonexcited state • Refractory period (in men): time following orgasm in the male during which he cannot experience another orgasm. (see chapter 5)

32. Changes in external female anatomy during sexual response Excitement phase: • engorgement of clitoris, labia minora, vagina, and nipples (vasocongestion); produces vaginal lubrication. • increase in muscle tension • increased heart rate and blood pressure Excitement phase Unaroused state

33. Changes in internal female anatomy during sexual response Excitement phase: • vaginal lubrication begins (due to vasocongestion) • clitoris engorges with blood • uterus elevates • increase in muscle tension, heart rate, and b.p. Excitement phase Unaroused state

34. Changes in external female anatomy during sexual response Plateau phase: • further increase in muscle tension, heart rate and b.p. • labia minora deepen in color • clitoris withdraws under its hood

35. Changes in internal female anatomy during sexual response Plateau phase: • further increase in muscle tension, heart rate and b.p. • orgasmic platform forms • clitoris withdraws under its hood • uterus becomes fully elevated

36. Changes in external female anatomy during sexual response Orgasm phase: • orgasmic platform (outer 1/3 of vagina) contracts rhythmically 3-15 times • clitoris remains retracted under hood

37. Changes in internal female anatomy during sexual response Orgasm phase: • uterine contractions (in addition to contractions of orgasmic platform)

38. Changes in external female anatomy during sexual response Resolution phase: • clitoris descends and engorgement subsides • labia return to unaroused size and color

39. Changes in internal female anatomy during sexual response Resolution phase: • uterus descends to unaroused position • vagina shortens and narrows back to unaroused state

40. Changes in the breasts during sexual response

41. (summarizes figures)

42. Historical misinformation about female orgasm • Sigmund Freud (early 1900s) • Developed theory of the “vaginal” vs. “clitoral” orgasm that led to misguided thinking about female sexual response for years • Theory stemmed from erroneous assumption that the clitoris was a “stunted penis,” so all erotic sensations from the clitoris were expressions of “masculine” rather than “feminine” sexuality-- therefore undesirable in a woman. • During adolescence, female was supposed to transfer her erotic center from her clitoris to her vagina--otherwise, she needed psychotherapy. • During Freud’s time, surgical removal of the clitoris was actually recommended for little girls who masturbated to help them later attain “vaginal” orgasms. • Cultural remnants still persist--women often feel uncomfortable asking partners for clitoral stimulation or stimulating clitoris herself b/c they believe they “should” experience orgasm from vaginal stimulation alone.

43. The “G” spot: what is it? • Stands for Grafenberg spot • From Ernest Grafenberg, a gynecologist who first publicized G spot in the 1950s. • Area of erotic sensitivity located along the anterior (front) wall of the vagina. • Some women are able to experience orgasm and possibly ejaculation from G spot stimulation. • G spot tissue is similar to male prostate; therefore, fluid may be similar to prostatic component of semen. • Supported by research that showed presence of enzyme in female ejaculate characteristic of prostate secretions • Note: orgasm from G spot stimulation is same as orgasm from clitoral stimulation, though intensity may vary depending on the method of stimulation.

44. The “G” spot: exploring • After becoming aroused . . . • Partner inserts two fingers, presses or taps firmly against anterior vaginal wall • Initial sensation may feel slightly uncomfortable, need to urinate, or pleasurable. • After a minute or more of stimulation, sensations usually become more pleasurable, and area may begin to swell. • Many toys available to help • Sexual exploration is always a good thing, but important not to treat the G-spot as a new sexual achievement to be relentlessly pursued.

45. Aging and the sexual response cycle • Women: (note: changes in sexual response vary considerably among women) • Some women report reduced desire • Reduced vasocongestion response, causing less and slower vaginal lubrication • Women who have more frequent sex (1-2 times weekly) lubricated more readily • Vaginal and urethral tissue loses some elasticity and becomes drier • Length and width of vagina decrease, reduced expansive ability of inner vagina during arousal. • Number of orgasmic contractions is often reduced. • More rapid resolution

46. Aging and the sexual response cycle • Men: (note: changes in sexual response vary considerably among men) • Longer time to develop an erection • i.e. several minutes of stimulation vs. 8-10 seconds • Erection may be less firm. • Complete penile erection is often not obtained until late in the plateau phase, just before orgasm. • On the plus side, older men are often more able to sustain the plateau phase longer, enhancing pleasure for both partners. • Some men report reduced intensity of orgasm • Reduced number of contractions, force of ejaculation is reduced, less semen produced. • More rapid resolution • Refractory period between orgasm and next excitement phase gradually lengthens (could be hours to days)

47. Sexual response:some differences between the sexes * There are many more similarities than differences in sexual response btwn. men and women.  Greater variability in female response  Male refractory period  Multiple orgasms • Some women can have >1 orgasm separated by brief periods of time (maybe only a few seconds) • All women are theoretically physiologically capable of experiencing multiple orgasms, though only about 15% of women report regularly having multiple orgasms • Some men can also experience multiple orgasms • These men report that withholding ejaculation is important for experiencing multiple orgasms--ejaculation often triggers refractory period.