Module 33 Page 1
Sexual Motivation and the Need to Belong
The Physiology of Sex
Sexual Response Cycle - the four stages of sexual responding described by Masters
and Johnson - excitement, plateau, orgasm and resolution
• Gynecologist-obstetrician William Masters and Virginia Johnson recorded
physiological responses of volunteers who masturbated or had sex
1. Excitement Phase M&W genitals become engorged with blood. W vagina
expands and secretes lubricant, breasts and nipples
2. Plateau Phase Breathing, pulse and blood pressure rates continually
increase. Penis becomes fully engorged and fluid with
live sperm at its tip. Vaginal secretion increases,
clitoris retracts and orgasm feels imminent.
3. Orgasm Pulse rates surge from 70-115 BPM. Woman's arousal
& orgasm facilitate conception by propelling semen
from the penis, positioning the uterus to receive sperm
and drawing it further inward. M&W's orgasms very
4. Resolution Phase Body returns to un-aroused state, genital blood
vessels release accumulated blood (quickly if orgasm
Refractory Period - a resting period after orgasm,
during which a man cannot achieve another orgasm.
Sexual Disorder - a problem that consistently impairs sexual arousal or functioning. Ex. Sexual
motivation or erectile dysfunction.
Estrogens - sex hormones such as estradiol, secreted in greater amounts by females than by
males and contributing to females sex characteristics. In nonhuman female mammals, estrogen
levels peak during ovulation, promoting sexual receptivity.
Around ovulation woman fantasize more about sex with desirable partners, wear more sexually
attractive clothing and have slightly higher pitch. Men's testosterone levels increase if around a Module 33 Page 2
woman ovulating Ex. Strippers hourly