Transcript Oct-10-sexual

Chapter 6
Sexual Arousal and Response
Last time:
• Cultural factors influence sexual arousal
• The cerebral cortex and limbic system
regulate sexual arousal
• Touch, sight, smell, taste, and sound all
contribute to arousal
• Aphrodisiacs enhance sexual desire and
performance, anaphrodisiacs inhibit these
things
HORMONES AND SEXUAL
AROUSAL
The Role of Hormones in Sexual
Behavior
• Steroid hormones (oily):
– Androgens (including testosterone)
• Produced by testes, adrenal glands, and ovaries
– Estrogens
• Produced by ovaries and testes
– Women and men produce both types
• Neuropeptide hormones (dissolve in water):
– Oxytocin: the “love hormone”
• Produced by the hypothalamus and released by the pituitary
gland
Sex Hormones in Male Sexual Behavior
• Testosterone
– Linked to sexual desire and genital sensitivity
– Castration leads to reduced sexual desire
– Antiandrogen drugs reduce testosterone in the
bloodstream and have a similar effect to castration
• Sometimes used to treat sex offenders, but doesn’t always
prevent them from re-offending
– Hypogonadism: testosterone deficiency due to
endocrine disease or, in some cases, aging
Sex Hormones in Female Sexual
Behavior
• Estrogens
– Overall link between estrogen and female sexual behavior is
unclear
– Estrogen Therapy (ET) in postmenopausal women is
reported to increase vaginal lubrication and sexual desire,
pleasure, and orgasmic capacity
• Perhaps an indirect effect of increased self-confidence
• Testosterone is the major libido hormone in females
• Testosterone treatment in women with low sex drive
increased it
• Women with higher sex drive tend to have naturally higher T
How Much Testosterone Is Necessary?
• Two forms of testosterone (5% free and 95% 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:
salt retention, fluid retention, hair loss, androgenizing
effects in women
• Testosterone levels decrease with age
– Fairly rapid decrease for women at menopause; more
gradual decline for men
• Testosterone Replacement Therapy occasionally
used to treat sexual dysfunction in men; more rare in
women
Oxytocin and Sexual Behavior
• The “love hormone”
– Also plays a role in trust
• Secreted during cuddling and physical intimacy
– Causes increased skin sensitivity
– High levels associated with orgasmic release for
women and men
– For women, stimulates contractions of uterine wall
during orgasm and during childbirth
SEXUAL RESPONSE
2 models of sexual response
• Masters and Johnson 1966: 4-stage model
• Helen Singer Kaplan 1979: 3-stage model
Kaplan’s 3-stage model of sexual response
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Master’s and Johnson’s Four Phases:
Excitement
Plateau
Orgasm
Resolution
• Two basic physiological processes
– Vasocongestion: engorgement of penis or vagina
with blood; other areas such as the nipples and
earlobes can also become engorged
– Myotonia: increased muscle tension during sexual
arousal
Sexual Response Cycle
Female Sexual Response
Male Sexual Response
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”
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
Sex Differences in Sexual Response
• Greater variability in female response
• Male refractory period
• Women can experience multiple orgasms