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The Human Sexual Response Amr Nadim, MD Professor of Obstetrics& Gynecology Ain shams Faculty of Medicine & The Women’s Hospital

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Presentation on theme: "The Human Sexual Response Amr Nadim, MD Professor of Obstetrics& Gynecology Ain shams Faculty of Medicine & The Women’s Hospital"— Presentation transcript:

1 The Human Sexual Response Amr Nadim, MD Professor of Obstetrics& Gynecology Ain shams Faculty of Medicine & The Women’s Hospital []

2 LEARNING OBJECTIVES By the end of this lecture, you should be able to:  Describe normal sexual response.  List common sexual problems and their definition.  List causes and management of frigidity, dyspareunia, and vaginismus.

3 Human Sexual Response Masters and Johnson: four phases Excitement/arousal Plateau Orgasm Resolution 1956-1966

4  The sexual response cycle in humans progresses through four phases: Excitement Plateau Orgasm (climax) Resolution


6  Males:  penile erection  scrotal sac thickens, elevates   Females :  vaginal lubrication  glans clitoris enlarges (similar to penile erection)  nipples erect (myotonia: muscle contraction)  breasts enlarge (vasocongestion  inner lips of vulva swell and open, change in colour (darker)  upper 2/3rds of vagina balloons  cervix and uterus stand up: tenting effect  angle of cervical opening more receptive to sperm Vasocongestion: pelvic area receives more blood in general, in particular to genitals. Excitation:  Both Sexes:  sex flush (can happen later)  heart rate, respiration rate gradually increase  generalized myotonia


8  Plateau: Both males and females continue vasocongestion to max Heart rate, respiration rate and blood pressure continue to increase Copious perspiration Increased myotonia

9  Females: orgasmic platform: outer third of vagina thickens, swells: condition sine qua non: without it, no orgasm tenting complete clitoris erect Plateau (Cont’d)

10  Males: Cowper’s glands secrete fluid through tip of penis. WARNING: may contain live sperm! scrotum even higher and testicles bigger Plateau (Cont’d)

11 Orgasm: Males: Two stages:  contraction of seminal vesicles, vas and prostate  contraction of urethra and penis: ejaculation

12 Orgasm: Females:  contractions of orgasmic platform  contractions of uterus  several orgasms possible if stimulation continues  oxytocin

13  Both: very high heart rate, blood pressure and breathing intense myotonia Orgasm:

14 Health Benefits Associated With Orgasm General Health  An orgasm at least once or twice per week appears to strength the immune system’s ability to resist flu and other viruses Pain Relief  Some women find that an orgasm’s release of hormones and muscle contractions help relieve the pain of menstrual cramps and raise pain tolerance in general. Better Sleep  The neurotransmitter dopamine, released during orgasm, triggers a stress-reducing, sleep-inducing response that may last up to two hours

15 Lower Cancer Rate  Men who have more than five ejaculations per week during their 20s have a significantly lower rate of prostate cancer later in life Mood Enhancement  Orgasms increase estrogen and endorphins, which tend to improve mood and ward off depression in women Greater Feelings of Intimacy  The hormone oxytocin, which may play a role in feelings of love and intimacy, increases fivefold at orgasm

16 Based on EEG, MRI and PET scans done in the lab while subjects having an orgasm. General emotional response:  coded in limbic association area, especially prefrontal cortex and cingulate gyrus. Pleasure:  coded in basal forebrain, especially ventral tegmental area and its dopaminergic stimulation of the reward centres of the septal nuclei and the nucleus accumbens. Euphoria:  probably by assymetric cortical activation The proportion and intensity of each varies with each orgasm. Emotional Changes During Orgasm

17 Return to normal, muscles relax, breathing etc. back to normal, blood back to circulation from genitals. Males  refractory period EACH PHASE MUST BE FULLY COMPLETED IN ORDER TO REACH THE NEXT ONE Resolution


19  Excitation: women slower:  cultural expectations, socialization  pregnancy  It is very important for male partner to make sure she is ready for plateau stage SOME GENDER DIFFERENCES

20  Plateau: without orgasmic platform women can’t have orgasm.  Orgasm: multiples for many women. Some women cannot go through resolution without several orgasms, vasocongestion persists.  Resolution: women have no refractory period

21  “Pleasure centers”: (for arousal and orgasm) Both:  genital area Women (and some men):  nipples, breasts, G-spot Men:  prostate Many body areas can be:  ears, back of knees, neck, feet, abdomen, thighs, inside of elbows, scalp

22  Retrograde Ejaculation: Two separate valves or sphincters, one to let urine into urethra, and another to let semen into urethra. When one is open, the other closes. In some cases, the semen valve is closed and the urinary valve that opens to the bladder is open. Semen flows into bladder. No ill effects.

23  Resolution: Men:  longer refractory periods, 24 hrs. midlife, longer in old age. Women:  no refractory periods ever.

24  Excitation: Men:  fastest 16-20 years, then show decline Middle Age:  very noticeable, need direct stimulation Old Age:  need lots of direct stimulation Women:  slower in teens, early 20s  faster 30’s on  Plateau: Men:  capacity for longer with age Women:  same, but never a big problem Each phase shows age changes

25 Orgasmic: Men:  intensity lessens from mid- to late 20s Middle Age:  really noticeable  ejaculate less volume, less forceful  Resolution: Refractory period increases

26 20 30 40 50 60 70 80 Age Intensity of Response Females Males


28 PHYSIOLOGY OF THE SEXUAL RESPONSE  Cognitive models: Kaplan’s triphasic model:  sexual desire  vasocongestion  muscular contraction Walen and Roth’s model:  emphasis on perception and evaluation, 8 steps, necessary for the arousal cycle to be completed

29 PHYSIOLOGY OF THE SEXUAL RESPONSE   Neural and hormonal involvement in sexual responses: Parasympathetic:  arousal Sympathetic:  orgasm Spinal reflexes:  erection and ejaculation Erection: sacral cord responds to stimulation, sends message via parasympathetic to relax penile arteries: more blood flows to penis. Also, message to brain, awareness (not if spine severed above sacrum) Ejaculation: higher in spinal cord, message to sympathetic that causes muscle contractions. Also, message to brain, awareness, possibility of control

30 Not yet well known Controversy surrounding G-spot and female ejaculation. One recent study found that sexual sensations can be transmitted to the brain via the vagus nerve, which is normally used for digestive processes. Women’s Neural Mechanisms:

31 PHYSIOLOGY OF THE SEXUAL RESPONSE  Higher Centres: limbic system: septal region of the amygdala

32 PHYSIOLOGY OF THE SEXUAL RESPONSE  Experiments using electrical stimulation: Erection centers found in the limbic system, both in monkeys and humans.

33 Most Studied Sex Hormone:  Testosterone produced by testes, ovaries and adrenal glands important for sexual desire in both sexes Hormonal Influences on Sex

34 Women have 1/10 th the amount but are ten times more sensitive to it. More testosterone in a normal person will not increase desire or response. Most testosterone is ‘bound’, not available in this regard, ‘free’ testosterone is 2-5%. Oxytocin, produced by the pituitary, important for female orgasm. Hormonal Influences on Sex

35 Chemistry of Attraction  DHEA (dehydroepiandrosterone): secreted by adrenal glands, weak androgen. Most sex hormones and pheromones derived from it. Same amount for males and females in bloodstream.  Pheromones: sexual signals for both sexes.  Oxytocin: released by the pituitary when touching or being touched by loved ones.

36 Chemistry of Attraction  PEA (phenylethylamine): called “the molecule of love”, produce euphoria, amphetamine-like substance produced in brain capillaries and in catecholaminergic terminals. Low PEA levels associated with depression (some depressions successfully treated with PEA). Some people become addicted to the PEA “high” and change partners frequently to get it, it is more abundant early in a relationship.

37 Chemistry of Attraction  Estrogen: makes women sexually attractive and receptive. Skin, lips, hair, fatty padding (curves), breasts, hips.  Testosterone: increases sex drive in both sexes, too much is counterproductive.  Endorphins: produced in the brain, released in response to touch and sex, produce positive feelings.  Progesterone: testosterone antagonist, lowers sex drive (in the pill as well), mild sedative, calming effect.

38 Chemistry of Attraction  Serotonin: neurotransmitter. At low levels intensifies sex drive, at high levels decreases it. Antidepressants elevate serotonin, decrease sex drive.  Dopamine: neurotransmitter associated with all pleasures, increases sex drive, promotes action.  Prolactin: decreases sex drive, especially in men.

39 Chemistry of Attraction  Vasopressin: hormone produced by the pituitary, antidiuretic (water retention), increases blood volume and blood pressure, identified as the “monogamy molecule”, modulates testosterone, levels extremes of feelings, increases focus in lovemaking.  All these substances fluctuate in a 24 hr. cycle, also with age and environmental events.  The “high” of early love is short-lived (6-30 months). Cultural belief in passionate love forever not realistic.

40 PHYSIOLOGY OF THE SEXUAL RESPONSE  Hormonal Influences on Sex (Cont’d): Hormones are NOT directly responsible for human sexual behaviour, as they are in most animals. Psycho-social context and culture are the most important determinants. In real life, people in good relationships say that sex is better than in casual situations.

41 PHYSIOLOGY OF THE SEXUAL RESPONSE  Anatomy and physiology of sex only give us an idea of how our biological equipment tends to work, but it does not give us an understanding of human sexual behaviour. Knowing car mechanics does not make you a good driver!  In order to get this, we need to explore our psychology, our communication styles, our culture/s, our interpersonal skills, etc.

42 Types of Sexual Dysfunction  Commonly the cause of sexual dysfunction is multifactorial and result in more than one dysfunction. Primary sexual dysfunction: Those who never had normal sexual activity. Secondary sexual dysfunction: Those who developed sexual dysfunction after a period of normal sexual activity.


44 Prevalence of Sexual Complaints in Women Laumann EO, et al. JAMA. 1999;281:537-544. *Women aged 18-59 years 32% 28% 21% 27% Percentage of Women* 43% of women experienced a sexual problem

45 Comorbidity of Anxiety and Depression With Sexual Problems Dunn KM, et al. J Epidemiol Community Health. 1999;53:144-148. *Odds ratio for association between anxiety and depression and sexual problems Increased association between anxiety or depression with sexual problems Odds Ratio*

46 Comorbidity of Marital Difficulties and Sexual Problems Dunn KM, et al. J Epidemiol Community Health. 1999;53:144-148. *Odds ratio for association between marital difficulty and sexual problems Increased association of marital problems with arousal, orgasm, or enjoyment problems Odds Ratio*

47 Female Sexual Dysfunctions Desire  Lack of sexual desire  Desire discrepancy with partner  Aversion to sexual activity Arousal  Difficulties with physical and/or subjective sexual arousal  Difficulties lubricating  Difficulties sustaining arousal Orgasm  Difficulties experiencing orgasm Pain  Pain with sexual activity  Difficulties with vaginal penetration (anxiety, muscle tension) Lack of sexual satisfaction and pleasure

48 Sexual desire disorders Hypoactive sexual desire disorder Sexual aversion disorder Sexual arousal disorder Female sexual arousal disorder Sexual orgasmic disorder Female sexual orgasm disorder Sexual pain disorders Dyspareunia Vaginismus Noncoital sexual pain disorder Basson R, et al. J Urol. 2000;163:888-893. Categories of Female Sexual Dysfunction

49 Female Sexual Dysfunction Physiological Neurological problems Cardiovascular disease Cancer Urogenital disorders Medications Fatigue Hormonal loss or abnormality Psychological Depression/anxiety Prior sexual or physical abuse Stress Alcohol/substance abuse Interpersonal relationships Partner performance and technique Lack of partner Relationship quality and conflict Lack of privacy Sociocultural influences Inadequate education Conflict with religious, personal, or family values Societal taboos

50 Sexual Desire Disorders  Hypoactive sexual desire disorder Absence of sexual fantasies, thoughts, and/or desire for, or receptivity to, sexual activity, which causes personal distress  Sexual aversion disorder Phobic aversion to and avoidance of sexual contact with a sexual partner, which causes personal distress Basson R, et al. J Urol. 2000;163:888-893.

51 Sexual Arousal Disorder  Female sexual arousal disorder Inability to attain or maintain sufficient sexual excitement, causing personal distress, which may be expressed as a lack of subjective excitement, or genital (lubrication/swelling) or other somatic responses Basson R, et al. J Urol. 2000;163:888-893.

52 Sexual Orgasm Disorder  Female orgasmic disorder Delay in or absence of attaining orgasm following sufficient sexual stimulation and arousal, which causes personal distress Basson R, et al. J Urol. 2000;163:888-893.

53  Incidence: - Anorgasmia among non circumcised females: ranges from 5-10%. Anorgasmia among circumcised females 48%.  Types of anorgasmia: A) Primary anorgasmia: Those who never had an orgasm under any sexual activity. - Early psychological trauma. - Social taboos. - Profound defect of personality. B) Secondary anorgasmia: 1- Situational anorgasmia: Transient causes include pregnancy, puerperium, fear of pregnancy, marital stress and dyspareunia 2- Coital anorgasmia: There is no orgasm during normal intercourse, but orgasm can be fulfilled during other alternatives as masturbation. It is failure to respond to normal stimulation. 3- Failure to receive stimulation: 1. Problems of sexual arousal during the excitement phase. 2. Failure of the husband to act at the excitement phase is a common problem.

54 Sexual Pain Disorders  Dyspareunia Genital pain associated with sexual intercourse  Vaginismus Involuntary spasm of the musculature of the outer third of the vagina that interferes with vaginal penetration, which causes personal distress  Noncoital sexual pain disorder Genital pain induced by noncoital sexual stimulation Basson R, et al. J Urol. 2000;163:888-893.

55 Dyspareunia  Etiology: Primary dyspareunia: it is often psychological  inadequate stimulation or forced inhibition of arousal leading to inadequate vaginal lubrication and coital pain.  Inadequate lubrication, may be secondary to improper or insufficient foreplay. Secondary dyspareunia: It is an acquired disorder, unrelated to the first coitus, and develops years later.  Organic causes of dyspareunia include the following: Superficial dyspareunia: 1)Vaginal opening (introital lesions): inflammatory conditions (e.g., vestibulitis), infections (e.g. herpes, abscesses of Bartholin's glands or ducts). - Tight introitus: secondary to episiotomy, plastic repair of the vagina or radiotherapy.

56 2) Vulval skin lesions: hymenal tears, laceration of the fourchette, painful superficial ulcerations, congenital septum, rigid hymen, and circumcision scar tissue. Dermatologic disorders as lichen sclerosis. 3) Clitoris and urethra: Irritations and infections, and suburethral diverticulum. 4) Vagina: Infections as vulvovaginitis (trichomonas or candida). Menopausal involution with dryness and thinning of the vaginal skin. 5) Reactions to local contraceptives: 1- Improperly fitted or inadequately lubricated condoms. 2- Allergic reactions to the contents of contraceptive foams, jellies and condoms. 6) Radiation therapy for malignancy

57 (B) Deep dyspareunia: 1. Endometriosis. 2. Pelvic inflammatory disease. 3. Marked retroflexion of the uterus with ovaries prolapsed into the cul-de-sac "ovarian entrapment syndrome". 4. Shortening of the vagina after surgery. Diagnosis: The location and nature of the pain may help in the diagnosis: 1- Deep dyspareunia: pain on deep thrusting at intercourse may indicate lesions of the uterus and/or broad ligament. 2- Local examination: introital lesions and uterine displacement or other pelvic pathology.

58 Treatment: 1) Existing lesions or defects should be corrected. 2) Advice husband on posterior intromission to avoid pressure on the sensitive urethra. 3) If the vulva is swollen and painful, a wet dressing of dilute aluminum acetate solution may be applied locally. An analgesic, is indicated if the pain is severe.

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