Chapter 4: Sexual Arousal and Response

Transcription

1 Chapter 4: Sexual Arousal and Response Role of senses in sexual arousal: - Vision o Visual cues can be sexual turn-on Penile response was greater in reaction to the slides of the more attractive women. o Men seem to be more interested by visual erotica - Smell o In western society, we are conditioned to find underarm or genital odours offensive and we remove or mask them with soaps, deodorants, and perfumes. o In some societies, genital secretions are considered aphrodisiacs any drug or other agent that is sexually arousing or increases sexual desire. o Pheromones Chemical substances that are secreted externally by certain animals and that convey info to, or produce specific responses in, other members of the same species. Odourless chemicals that in many animals are detected through a sixth sense the vomeronasal organ (VNO) People possess VNOs in the mucous lining of the nose. Infants apparently use pheromones to recognize their mothers, and adults might respond to them in seeking a mate. o Menstrual Synchrony Exposure to other women s sweat can modify a woman s menstrual cycle. o Attraction to or dislike of body odours of heterosexual males and females versus gay males and lesbians Body odours play a role in the selection of sex partners. Preferences for axillary (underarm) odours would be related to people s sexual orientation - Skin senses sex as a touching experience o Sense of touch has the most direct effects on sexual arousal and response. o Erogenous zones parts of the body that are especially sensitive to tactile sexual stimulation (strokes and caresses) o Primary erogenous zones erogenous zones that are particularly sensitive because they are richly endowed with nerve endings Include genitals, inner thighs, perineum, buttocks, anus, breasts (especially nipples), ears, mouth, lips, tongue, neck, navel, and armpits o Secondary erogenous zones parts of the body that become erotically sensitized through experience (eg. Caressing shoulders while making love) - Taste o Some people are sexually aroused by the taste of genital secretions, such as vaginal secretions or seminal fluid. - Hearing o People have different preferences to the sounds made when having sex (from moans, to whispers, to dirty talk) o Music can contribute to sexual arousal. Can relax us and put us in the mood Aphrodisiacs - An aphrodisiac is a substance that arouses or increases one s capacity for sexual pleasure or response. o However, the belief that a substance has sexually stimulating effects may itself inspire sexual excitement. - Food that in some way resemble male genitals have been considered aphrodisiacs o Oyster,s clams, bulls testicles, tomatoes, and phallic items like celery stalks, bananas, and even ground up reindeer antlers, elephant tusks, and rhinoceros horns Rhinoceros horns one derivation of the slang term horny - Drugs and psychoactive substances may have certain effects on sexual arousal and response. o Arginine amino acid extracted from the African yohimbe tree, stimulates blood flow to the genitals. However, effects are limited and unreliable. o Amyl nitrate (in the form of poppers or snappers) Used mostly by gay men, but heterosexuals use it too Believed to heighten the sensations of arousal and orgasm poppers dilate blood vessels in the brain and genitals, producing sensations of warmth in the pelvis and possible facilitating erection and prolonging orgasm has legitimate medical uses, like reduce heart pain among cardiac patients o Viagra Originally developed for heart pain because it was thought that it would increase the blood flow to the heart.

2 However, it is more effective at dilating blood vessels in the genital organs, thereby facilitating vasocongestion and erection in the male. Viagra is not an aphrodisiac (it facilitates erection, but it doesn t directly turn you on) - Most potent chemical aphrodisiac may be a naturally occurring substance in the body the hormone testosterone. o Basic fuel of sexual desire in both males and females. - Best and safest way to increase sex drive exercise o Regular exercise enhances general health, boosts energy, and increases sex drive in both genders. - Routine can diminish desire - Anaphrodisiacs drugs or other agents whose effects are antagonistic to sexual arousal or sexual desire. - Anti-androgen drug that reduces the levels of androgens in the blood system. - Psychoactive drugs, such as alcohol and cocaine, are widely believed to have aphrodisiac effects. o Alcohol Small amounts of alcohol are stimulating, but large amounts curb sexual response. Large amounts of alcohol can severely impair sexual performance in both men and women. People who drink moderate amounts of alcohol may feel more sexually aroused because of their expectations about alcohol, not because of its chemical properties. Alcohol is a depressant, and can reduce sexual potency rather than restore it. - Hallucinogenics o Marijuana, LSD, and mescaline have been reported by some users to enhance sexual response. These effects may reflect dosage level and user expectations, experiences, and attitudes toward the drugs, as well as altered perceptions. - Stimulants o Stimulants such as amphetamines have been reputed to heighten arousal and sensations of orgasm. high does can give rise to irritability, restlessness, hallucinations, paranoid delusions, insomnia, and loss of appetite. These drugs generally activate the central nervous system but are not known to have specific sexual effects. Nevertheless, arousing the nervous system can contribute to sexual arousal. The drugs can also elevate the mood, so sexual pleasure is perhaps heightened by general elation. o Cocaine is a natural stimulant There is evidence that cocaine enhances sexual arousal in both males and females, in part by increasing levels of the neurotransmitter dopamine. Use of crack cocaine is connected with higher number of sex partners o Crystal meth is being used as an aphrodisiac that boosts sexual arousal and lowers sexual inhibitions. Most addictive and most difficult to treat - Many new users of various recreational drugs report that these drugs enhance their sexual experience; however, extensive use of these drugs usually results in diminished sexual functioning as well as numerous negative effects on the users general health. Sexual response and the brain: Cerebral Sex? - The brain may not be an erogenous zone, but it plays an important part in sexual functioning. - Direct genital stimulation may trigger spinal reflexes that produce erection in the male and vaginal lubrication in the female w/o the direct involvement of the brain. o the same reflexes may be triggered by sexual stimulation that originates in the brain in the form of erotic memories, fantasies, visual images, and thoughts. - Cerebral cortex wrinkled surface area (grey matter) of the brain o Cells in the cerebral cortex transmit messages when we experience sexual thoughts, images, fantasies, etc. o Interpret sensory information as sexual turn-ons or turn-offs o Messages sent to the spinal cord send blood rushing to the genitals, causing erection or vaginal lubrication. o Provides the conscious sense of self. - Limbic system a group of structures active in memory, motivation, and emotion; the structures that are part of this system form a fringe along the inner edge of the cerebrum. Sex hormones and sexual behaviour - Hormones a substance that is secreted by an endocrine gland and regulates various body functions. - Sex hormones released at puberty cause the flowering of secondary sex characteristics physical traits that differentiate males from females but are not directly involved in reproduction o In males voice changes, growth of facial & pubic hair o In females breasts and hips become rounded with fatty tissue, growth of pubic hair - Sex hormones have organizing and activating effects on behaviour.

3 o They exert and influence on the type of behaviour that is expressed (an organizing effect) and on the frequency or intensity of the drive that motivates the behaviour and the ability to perform the behaviour (activating effects). - Prenatal sex hormones are known to play a role in the sexual differentiation of the genitalia and of the brain structures, such as hypothalamus. o Brains of transsexual individuals may have been prenatally sexually differentiated in one direction while their genitals were being differentiated in the other. o Transsexual a person with a gender-identity disorder who feels that he or she is really a member of the other gender and is trapped in a body of the wrong gender o Prenatal sexual differentiation of the brain may also be connected with sexual orientation - Sex hormones and male sexual behaviour o Testosterone is important in maintaining sexual functioning as well as drive. o Male sexual motivation and functioning involve and interplay of hormonal influences and experience. o Hypogonadism an abnormal condition marked by abnormally low levels of testosterone production. o At puberty, hormonal variations play a more direct role in stimulating sexual interest and activity in males. - Sex hormones and female sexual behaviour o The female sex hormones estrogen and progesterone play prominent roles in promoting the changes that occur during puberty and in regulating the menstrual cycle. o Female sex hormones do not appear to play a direct role in determining sexual motivation or response in human females. o Estrogen peaks at times of ovulation close relationship between fertility and sexual receptivity in most female mammals. o Women s sexuality is not clearly linked to hormonal fluctuations. o Unlike most mammalian females, the human female is sexually responsive during all phases of the reproductive cycle even during menstruation, when ovarian hormone levels are low and after menopause. o There is some evidence that sexual responsiveness in women is influenced by the presence of circulating androgens, or male sex hormones, in their bodies. the adrenal glands of women produce small amounts of androgens, just as they do in males. o Ovariectomies surgical removal of the ovaries Sometimes carried out when a hysterectomy is performed No longer produce female sex hormones. Nevertheless, they continue to experience sex drives and interest as before. Loss of the the ovarian hormone estradiol may cause vaginal dryness and make coitus painful, but it does not reduce sexual desire. o Women whose adrenal and ovaries have been removed (so that they no longer produce androgens) gradually lose sexual desire. o Androgen levels were found to predict sexual interest among teenage girls. o Other researchers report that women s sexual activity increases at points in the menstrual cycle when levels of androgens in the bloodstream are high. o Androgens play a more prominent role than ovarian hormones in activating and maintaining women s sex drives. Sexual Response - Sexual response cycle Masters and Johnson s model of sexual response, which consists of four phases - The Four-Phase Masters and Johnson Sexual Response Cycle o Phase 1: excitement o Phase 2: plateau o Phase 3: orgasm o Phase 4: resolution - Vasocongestion the swelling of the genital tissues with blood, which causes erection of the penis and engorgement of the area surrounding the vaginal opening. - Myotonia Muscle tension o Causes voluntary and involuntary muscle contractions, which produce facial grimaces, spasms in the hands and feet, and eventually, the spasms of orgasm. - Excitement phase the first phase of the sexual response cycle, which is characterized by erection in the male, by vaginal lubrication in the female, and by muscle tension and increases in heart rate in both males and females. - sex flush a reddish rash that appears on the chest or breasts late in the excitement phase of the sexual response cycle. - Plateau phase the second phase of the sexual response cycle, which is characterized by increases in vasocongestion, muscle tension, heart rate, and blood pressure in preparation for orgasm. - Orgasmic platform the thickening of the walls of the outer third of the vagina, due to vasocongestion, that occurs during the plateau phase of the sexual response cycle.

4 - Sex skin the reddening of the labia minora that occurs during the plateau phase - Orgasmic phase o Orgasmic phase in the male consists of two stages of muscular contractions First stage contractions of the vas deferens, the seminal vesicles, the ejaculatory duct, and the prostate gland cause seminal fluid to collect in the urethral bulb at the base of the penis. The bulb expands to accommodate the fluid The internal sphincter of the urinary bladder contracts, preventing seminal fluid from entering the bladder in a backward, retrograde ejaculation. The normal closing off of the bladder also serves to prevent urine from mixing with semen. The collection of semen in the urethral bulb produces feelings of ejaculatory inevitablilty the sensation that nothing will stop the ejaculate from coming Second stage the external sphincter of the bladder relaxes, allowing the passage of semen. Contractions of muscles surrounding the urethra and urethral bulb and the base of the penis propel the ejaculate through the urethra and out of the body. Sensations of pleasure tend to be related to the strength of the contractions and the amount of seminal fluid. The first three to four contractions are generally most intense o Orgasm in the female is manifested by 3 to 15 contractions of the pelvic muscles that surround the vaginal barrel. - Resolution phase the fourth phase of the sexual response cycle, during which the body gradually returns to its prearoused state. o Following ejaculation, the man loses his erection in two stages: Stage 1 occurs in about a minute Half the volume of the erection is lost, as blood from the corpora cavernosa empties into the other parts of the body Stage 2 occurs over a period of several minutes The remaining tumescence subsides as the corpus spongiosum empties. The testes and scrotum return to normal size, and the scrotum regains its wrinkled appearance. o In women, orgasms also triggers release of blood from engorged areas. In the absence of continued stimulation, swelling of the areolas decreases, then the nipples return to normal size. Sex flush lightens rapidly Clitoris descends to its normal position Clitoris, vaginal barrel, uterus, and labia gradually shrink to their prearoused sizes. Labia minora turn lighter Sex skin disappears o most myotonia tends to dissipate within 5 minutes after orgasm in both men and women. o Blood pressure, heart rate, and respiration may also return to their prearousal levels within a few minutes o Most people are Covered in sweat o Unlike women, men enter a refractory period during which they are physiologically incapable of experiencing another orgasm or ejaculation. Lasts minutes in younger men The older you get, the longer it takes o Myotonia and vasocongestion may take an hour or more to dissipate in people who are aroused who do not reach orgasm. - Kaplan s three stages of sexual response: 1) desire 2) excitement 3) orgasm Basson s Intimacy Model of Female Sexual response: o Criticizes other models because they don t take into account the factor on intimacy. o According to Basson, most women in longer-term relationships are motivated to respond to sexual stimuli if they feel that becoming sexually involved will enhance intimacy with their partner. o Often a woman will begin sexual encounters with a nonsexual or neutral state of mind. Once the woman has begun to become sexually aroused for intimacy reasons, she will continue the experience for sexual reasons. At this point she will be responsive to sexual stimulation, such as breast or genital touching, that will increase her arousal.

5 o If the woman finds the outcome to be both physically and emotionally satisfying, it will increase her feeling of intimacy with her partner and motivate her to become sexually involved again in the future. This model allows for the possibility that arousal may precede sexual desire and that arousal may not lead to orgasm Controversies about orgasm: Multiple orgasms o Men are not capable of achieving multiple orgasms because they enter a refractory period (according to masters and Johnson) o Women do not enter a refractory period can undergo multiple orgasms o Some men can train themselves to have two or more orgasms without ejaculation (dry orgasms) o A common belief is that for men, ejaculation defines orgasm. o This is not true. Types of orgasms: o People believe that there are two types of orgasms: clitoral and vaginal o However, masters and Johnson were able to find only one, regardless of the source of stimulation Sex and disability o According to Margaret Nosek and her colleagues, sexual wellness, even among the disabled, involves five factors: o Positive sexual self-concept; seeing oneself as valuable sexually and as a person o Knowledge about sexuality o Positive, productive relationships o Coping with barriers to sexuality o Maintaining the best possible general and sexual health, given one s limitations. o Multiple sclerosis o Chronic, unpredictable disease that affects the nervous system. o MS impairs sexual functioning, and people with MS report more sexual problems o Cerebral palsy o A muscular disorder that is caused by damage to the central nervous system (usually prior to or during birth) and is characterized by spastic paralysis. o Does not generally impair sexual interest, capacity for orgasm, or fertility. o Depending on the nature and degree of muscle spasticity or lack of voluntary muscle control, however, afflicted people may be limited to certain types of sexual activities and coital positions. o Often socialized into an asexual role. o Spinal cord injuries o Loss of voluntary control can occur in either the legs or all four limbs o A loss of sensation may also occur in parts of the body that lie beneath the site of injury. o Effect on sexual response depends on the site and severity of the injury o Men have 2 erection centre on the spinal cord: a higher centre in the lumbar region and a lower one. When damage occurs at or above the level of the lumbar centre, men lose the capacity for psychogenic erections (responding to mental stimulation alone) They may still be able to achieve reflexive erections from direct stimulation of the penis, but they can t feel any genital sensations. Men with damage to the lower sacral erection centre lose the capacity for reflexive erections but can still achieve psychogenic erections so long as their upper spinal cord remains intact. o Most women with spinal cord injuries can engage in coitus, become pregnant, and deliver vaginally. o Sensory disabilities o Blindness, deaf, etc. o Do not directly affect genital responsiveness o Blind people may not understand anatomy of genitals o Deaf people may not understand social cues involved in forming and maintaining intimate relationships o Arthritis a progressive disease characterized by inflammation or pain in the joints o May make it difficult to bend arms, knees and hips during sexual activity o Psychological disabilites: o Stereotyped as incapable of understanding their sexual impulses o Some stereotype them as having stronger than normal sex drives and incapable of controlling them

6 Sexuality can enrich the lives of nearly all adults at virtually any age.