Sexual Arousal and Response

Hormones in sexual arousal 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 (dissolve in water): –Oxytocin: the “love hormone” Produced by the hypothalamus and released by the pituitary gland

Control of Hormones

Sex Hormones in Male Sexual Behavior Testosterone –Linked to sexual desire and genital sensitivity –Castration leads to reduced sexual desire –Anti-androgen 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 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 testosterone levels-testosterone is produced by the ovaries and adrenal glands in low levels.

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

Master’s and Johnson’s Four Phases Model of Sexual Arousal: 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

Orgasm Shortest phase of sexual response cycle –Male orgasms consist of two stages of muscular contractions. 1 st stage: contractions push seminal fluid into urethral bulb 2 nd stage: ejaculation –Female orgasms involve contractions in the pelvic muscles, uterus, and anal sphincter. 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” –In both men and women, muscle spasms occur throughout the body and blood pressure and heart rate peak.

Nitric Oxide-Vasodilation

Copyright 2008 Allyn & Bacon Sexual Response

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

Sexual Response Cycle