The Physiology of Sexual Response Chapter 9 The Physiology of Sexual Response Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-1

Masters and Johnson Four stages of sexual response: Excitement Plateau Orgasm Resolution Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-2

Masters and Johnson Two basic physiological processes that occur during these stages: Vasocongestion Myotonia Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-3

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Excitement Vasocongestion occurs - accumulation of blood in the blood vessels of a region of the body Vagina lubricates, glans of clitoris swells, nipples become erect Sex flush may appear Increase in pulse rate and blood pressure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-6

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Plateau Vasocongestion reaches its peak In females the orgasmic platform forms - tightening of the entrance to the vagina Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-8

Orgasm In males, orgasm consists of a series of rhythmic contractions of the pelvic organs at 0.8 second intervals In males and females there is a sharp increase in pulse rate, blood pressure, and breathing rate Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-9

Resolution Body returns to the unaroused state Phase takes about 15 to 30 minutes Gradual return of pulse rate, blood pressure, and breathing rate to the unaroused levels Refractory period - time during which men are incapable of being aroused again, have an erection, or have an orgasm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-10

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Other Findings of the Masters and Johnson Research Clitoral orgasm versus vaginal orgasm Multiple orgasm - a series of orgasms occurring within a short period of time Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-13

Cognitive-Physiological Models Kaplan’s Triphasic Model: Sexual desire Vasocongestion Muscular contractions Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-14

Walen and Roth: A Cognitive Model Perception Evaluation Arousal Perception of arousal Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-15

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Hormonal and Neural Control of Sexual Behavior The brain, spinal cord and sex Spinal reflexes Three components of a reflex: Receptors Transmitters Effectors Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-17

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Mechanism of Erection Erection is produced by a spinal reflex It can also be produced by tactile stimulation of the genitals, and fantasy Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-19

Mechanism of Erection Mechanism of Ejaculation - ejaculation center is located higher in the spinal cord than the erection reflex Retrograde ejaculation - a condition in which orgasm in the male is not accompanied by an external ejaculation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-20

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Mechanisms in Women Female ejaculation Grafenberg spot - small region on the front wall of the vagina, emptying into the urethra, and responsible for female ejaculation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-22

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Brain Control of Sexual Response Limbic system - set of structures in the interior of the brain, including the amygdala, hippocampus, and fornix; believed to be important for sexual behavior in both animals and humans Sex centers or pleasure centers Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-24

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Hormones and Sex Organizing effects - effects of sex hormones early in development, resulting in a permanent change in the brain or reproductive system Activating effects - effects of sex hormones in adulthood, resulting in the activation of behaviors, especially sexual behaviors and aggressive behaviors Testosterone and sexual desire Testosterone has effects on libido in males Androgens are related to sexual desire in women Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-26

Pheromones Biochemicals secreted outside the body that are important in communication between animals and that may serve as sex attractants May play an important role in sexual behavior Menstrual synchrony - convergence, over several months, of the dates of onset of menstrual periods among women who are in close contact with each other Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-27