For adult learner

1. Chapter 6
Sexual 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 6.2
List 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
Unaroused state Excitement phase

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.
Unaroused state Excitement phase

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.