Summary made by Car da Silva van der Meer - PSB3E-M20 Capita Selecta Human Sexology
Chapter 3: The Physiology of Human Sexual Responding
Since you asked:
1. How can we know for sure what happens during sex? You can’t exactly study people while
they’re doing it, right? (page 75)
To study the physiological response during sexual activity and stimulation, they
measured standard physiological responses such as pulse, blood pressure and rate of
respiration, and observed/recorded specific sexual responses. They recorded sexual activity
with heterosexual couples in different sex positions and during masturbation.
2. Are aphrodisiacs for real? Which ones really work? (page 78)
Throughout history it’s believed some chemicals, foods, drinks etc produce sexual
desire in humans; aphrodisiacs. Science has yet to provide any evidence that true aphrodisiacs
exist, thus they remain a myth. Maybe more of a placebo effect.
3. What is ‘pre-cum’ and why does it appear? (page 81)
Cowper’s glands secreted pre-ejaculate fluid (‘pre-cum’). This fluid is to produce
additional lubrication for intercourse and may serve to flush out the urethra prior to
ejaculation of semen. It has live sperm cells and may have infection-causing microbes.
4. I am a woman. During intercourse, why does it take so long for me to have an orgasm? Is it
unusual for women to not have orgasms during sex? (page 82)
Women tend to require more stimulation than men to achieve orgasm with a partner,
the majority of women do not routinely experience orgasm through intercourse exclusively.
Penile penetration may be pleasurable but won’t generally lead to orgasm, and orgasm may
not be the main motivation for intercourse for women. Most require additional stimulation to
the clitoral area before, during or after intercourse.
5. Do orgasms feel the same to men and women? Are men’s stronger or more intense? (page 83)
Men and women report orgasms as about the same.
6. Are too many orgasms dangerous to your health? How many are too many? (page 85)
Orgasms can be good for general health (orgasming twice a week increases the
immune system), pain relief, lower cancer rates, mood enhancement, longer life, greater
feelings of intimacy, less heart disease, better sleep and younger appearance. However,
lovemaking should be pleasure-directed, not orgasm-as-goal.
7. After I orgasm, I can get another erection pretty fast, but I can’t seem to orgasm again. Is this
normal or a problem of some kind? (page 85)
Ejaculation does not necessarily occur with each orgasm.
8. I’ve heard that some women ejaculate like men. Is this true? How is it possible? (page 86)
Two theories, either it’s urine caused by incontinence or it’s due to Skene’s Glands.
9. Exactly what and where is the ‘G-spot’? My boyfriend and I can’t seem to find it! (page 87)
The G-spot is 1-2 inches into the vagina on the anterior wall.
10. I’ve heard that there is a new pill for women that works like Viagra for men. Is this true?
What does it do? (page 91)
‘Pink Viagra’ enhances female sexual response.
The physiology of sex is how our sexual structures function and produce our ability to respond
physically and emotionally to sexual stimulation. Anatomy and physiology are not the same. This
chapter evolves what happens to the body before during and after sexual activity, both solo and with a
partner, and explores physical changes that come with sexual desire, excitement, orgasm and
1
,Summary made by Car da Silva van der Meer - PSB3E-M20 Capita Selecta Human Sexology
resolution (returning to a non-aroused state), and classifies the similarities and differences in the
response of men and women.
Historical Perspective
Sexual Pioneers
A large portion of research on sexual behaviour prior to 1960 was done by Alfred Kinsley in the late
40s and 50s. His team surveyed thousands about their sexual behaviour and attitudes and reported on
a variety of topics, including frequency of intimacy and masturbation habits to homosexual
experiences. It has a lot of research about what people self-report, leaving a gap in how human bodily
function anatomically engaged in sexual activity.
William H. Masters and Virginia E. Johnson changed chat in the 60s. Their research on
human sexual physiology and response revealed to the world how our sexual bodies function during
sexual activity. This started the sexual revolution in the United States and the ‘free love’ movement.
This was an opportunity for candid and definitive scientific exploration of our sexuality that would
not have been possible before, as before sexual activity was seen as something to be quiet and
secretive about. To study the physiological response during sexual activity and stimulation, they
measured standard physiological responses such as pulse, blood pressure and rate of respiration, and
observed/recorded specific sexual responses. They recorded sexual activity with heterosexual couples
in different sex positions and during masturbation. Their book Human Sexual Response (1966) was
very important for many years to come. They later released more books, including Human Sexual
Inadequacy (1970), with both sexual dysfunctions and solutions, The Pleasure Bond (1974),
Homosexuality in Perspective (1979), Masters and Johnson on Sex and Human Loving (1986) and
Crisis: Heterosexual Behaviour in the Age of AIDS (1988). Their last book was Heterosexuality
(1994).
Biology, Psychology, and Human Sexual Responding
Though humans are animals, our sexual response is not solely governed by biological factors. Our
willingness to have sex is not clearly linked to a female's menstrual cycle. Psychology plays a role just
as great, if not greater, than biology in our sexual behaviour. Besides reproduction we may want to
have sex or masturbate to feel pleasure, give pleasure, experience intimacy, stress relief, feeling
valued by another, express value in another, feel more/less dominant/submissive and a myriad of other
reasons.
Masters and Johnson: the Excitement-Plateau-Orgasm-Resolution model
Like all researchers, Masters and Johnson made mistakes and thus not all conclusions are universally
accepted. Later in chapter 3 other theories on the sexual response cycle will be discussed. But for now,
Masters and Johnson created this one, involving 4 stages, Excitement, Plateau, Orgasm and
Resolution, or EPOR Model. It’s fundamentally impossible to know when excitement ends and where
the plateau begins, but the model was easy to understand.
Keep in mind sex is more than intercourse, and these can
occur during more than just intercourse, such as during oral,
masturbation or wet dreams.
Excitement
Involves early physical responses to any type of pleasurable
sexual stimulation. What triggers sexual arousal depends on
individual and cultural factors. Throughout history it’s
believed some chemicals, foods, drinks etc produce sexual
2
,Summary made by Car da Silva van der Meer - PSB3E-M20 Capita Selecta Human Sexology
desire in humans; aphrodisiacs. Science has yet to provide any evidence that true aphrodisiacs exist,
thus they remain a myth.
For both sexes, blood circulation increases to all erectile structures and causes them to expand
and stiffen; Vasocongestion. A sex flush, nipples become erect, breathing becomes heavier, heart rate
increases and voluntary muscles tense in a process called myotonia.
In men, one sign of sexual excitement is penile erection, tightening on scrotal skin and
testicles enlarging and risking up towards the underside of the penis. Erection may be lost if
stimulation is stopped or concentration wanders. Men may worry about loss of erection throughout the
sexual activity and this worry of (normal) fluctuation of penile erection may become a self-fulfilling
prophecy.
In women, the first sign of sexual excitement is vaginal lubrication and the clitoris becoming
erect. Internally the uterus engorges with blood and moves slightly upward in the abdomen, and may
exhibit fibrillation. The vagina becomes longer and widens out along the inner two-thirds of its length.
Breasts, nipples and areolas enlarge slightly (in both men and women).
Plateau
The plateau phase is when arousal seems to level off and remains at an elevated level of excitement.
All erectile tissue is engorged with blood. Respiration, heart rate, blood pressure and muscle tension
are all at high levels as orgasm approaches. In women, nipples remain erect and areolas continue to
become larger. The walls of the outer one-third of the vagina are engorged with blood and thickened,
reducing the size of the vaginal opening. This stimulates the penis during intercourse to ensure male
orgasm and ejaculation, but this occurs whether or not intercourse is taking place. The inner
two-thirds of the vagina continues to expand; Tenting. Tenting creates a place for semen to pool
directly under the cervix and stimulate it with hormones in seminal fluid to suck sperm into the uterus.
Clitoris continues to engorge and glands hide under the clitoral hood. Due to this, it’s less sensitive to
stimulation, and to reach orgasm during sexual intercourse there may be more stimulation needed.
This is why many women report other activities besides intercourse to be more satisfying. The labia
minora deepens in colour.
In men, the penis is fully erect and unlikely to be lost unless there is a major distraction.
Cornea enlarges and Cowper’s glands secreted pre-ejaculate fluid (‘pre-cum’). This fluid is to produce
additional lubrication for intercourse and may serve to flush out the urethra prior to ejaculation of
semen. It has live sperm cells and may have infection-causing microbes. The scrotal skin is tight, and
testicles are pulled close to the body.
Orgasm
The orgasmic phase only lasts about 15 seconds. Orgasms vary in characteristics and intensity from
person to person and depend on the sexual experience and how orgasm is achieved. Women tend to
require more stimulation than men to achieve orgasm with a partner; the majority of women do not
routinely experience orgasm through intercourse exclusively. Penile penetration may be pleasurable
but won’t generally lead to orgasm, and orgasm may not be the main motivation for intercourse for
women. Most require additional stimulation to the clitoral area before, during or after intercourse.
Orgasm is the result of direct or indirect stimulation of the clitoris, but due to the sensitivity of the
clitoris, direct stimulation may be too intense. Factors influencing the intensity and duration of orgasm
may be arousal prior to orgasm, time since the last orgasm, drug/alcohol use and level of
comfort/intimacy with a partner. Respiration increases dramatically, and pulse rate and blood pressure
continue to rise. Sexual flush spreads over the body. Loss of control of voluntary muscles causes
contraction and spasms. Muscles in the pelvic area contract at a rate of about 0.8 seconds.
3
, Summary made by Car da Silva van der Meer - PSB3E-M20 Capita Selecta Human Sexology
For women, the anus, uterus, pelvic floor muscles and walls of the outer third of the vagina
contact in intervals of 0.8 seconds, the number of contractions vary from 3 to 15.
For men, contraction of the anus and ejaculation. Ejaculation occurs in 2 stages; emission
(semen build-up in the urethral bulb, leads to a point of no return or Ejaculatory inevitability. After
emission, the prostate gland, urethra and muscles at the base of the penis contracts at intervals of 0.8
seconds) and expulsion (pushing semen through the urethra).
After orgasm, individuals are left in a stage of satisfied, warm sensations of emotional
well-being, aka the afterglow, facilitated by oxytocin.
Male and female descriptions of orgasms are very similar. Intercourse should be pleasure
directed instead of orgasms directed, as orgasm as the goal approaches leads to bland, repetitive and
non-intimate intercourse.
Variation in Orgasm
Though Masters and Johnsons claim women are capable of multiple orgasms and men pass through a
refractory period between orgasms, that conclusion is oversimplified. Men are capable of
experiencing multiple orgasms without loss of erection and ejaculation is not necessary with each
orgasm. However, documentation of multiple orgasms in men is small. Women who report multiple
orgasms during intercourse report similar levels of sexual satisfaction as women who report single
orgasms during sexual intercourse. Some women may orgasm multiple times during masturbation,
oral stimulation or vibrator use but only single during heterosexual intercourse.
Female Ejaculation and the “G-Spot”
The phenomenon of female ejaculation is subject to debate with two questions; do some women really
ejaculate upon orgasm and if so, what does female ejaculation consist of? Some claim the fluid
expelled by women upon orgasm is identical to urine, and some think it's more akin to semen. If it’s
urine, it may be due to contraction leading to incontinence (like how some people have stress
incontinence when laughing too hard). Several studies found that female ejaculation resembles male
prostatic fluid in chemical components, and women who report ejaculation do not appear more prone
to urinary stress incontinence.
Some assume fluid is secreted by two paraurethral glands known as Skene’s glands. They may
secrete fluid into the urethra at the moment of orgasm, though the purpose is unclear. As it is
expressed through the urethra and not the vagina it wouldn’t
significantly help lubrication. Women who ejaculate report
intense pleasure.
In the 80s a structure linked to the intensity of female
orgasm was ‘discovered’, by Ernst Grafenberg, thus named
Grafenberg spot or G-spot. The G-spot is located in the
anterior wall of the vagina about 1-2 inches from the vaginal
opening. It’s a slightly raised area about the size of a dime
during sexual stimulation. This spot is hard to find and thus
some researchers say it doesn’t exist. To find the G-spot,
place one or two fingers inside the vagina and press up
against the wall in a massaging motion. Some report that if
g-spot is stimulated during sexual activity, arousal and
orgasms are enhanced and intensified.
4
Chapter 3: The Physiology of Human Sexual Responding
Since you asked:
1. How can we know for sure what happens during sex? You can’t exactly study people while
they’re doing it, right? (page 75)
To study the physiological response during sexual activity and stimulation, they
measured standard physiological responses such as pulse, blood pressure and rate of
respiration, and observed/recorded specific sexual responses. They recorded sexual activity
with heterosexual couples in different sex positions and during masturbation.
2. Are aphrodisiacs for real? Which ones really work? (page 78)
Throughout history it’s believed some chemicals, foods, drinks etc produce sexual
desire in humans; aphrodisiacs. Science has yet to provide any evidence that true aphrodisiacs
exist, thus they remain a myth. Maybe more of a placebo effect.
3. What is ‘pre-cum’ and why does it appear? (page 81)
Cowper’s glands secreted pre-ejaculate fluid (‘pre-cum’). This fluid is to produce
additional lubrication for intercourse and may serve to flush out the urethra prior to
ejaculation of semen. It has live sperm cells and may have infection-causing microbes.
4. I am a woman. During intercourse, why does it take so long for me to have an orgasm? Is it
unusual for women to not have orgasms during sex? (page 82)
Women tend to require more stimulation than men to achieve orgasm with a partner,
the majority of women do not routinely experience orgasm through intercourse exclusively.
Penile penetration may be pleasurable but won’t generally lead to orgasm, and orgasm may
not be the main motivation for intercourse for women. Most require additional stimulation to
the clitoral area before, during or after intercourse.
5. Do orgasms feel the same to men and women? Are men’s stronger or more intense? (page 83)
Men and women report orgasms as about the same.
6. Are too many orgasms dangerous to your health? How many are too many? (page 85)
Orgasms can be good for general health (orgasming twice a week increases the
immune system), pain relief, lower cancer rates, mood enhancement, longer life, greater
feelings of intimacy, less heart disease, better sleep and younger appearance. However,
lovemaking should be pleasure-directed, not orgasm-as-goal.
7. After I orgasm, I can get another erection pretty fast, but I can’t seem to orgasm again. Is this
normal or a problem of some kind? (page 85)
Ejaculation does not necessarily occur with each orgasm.
8. I’ve heard that some women ejaculate like men. Is this true? How is it possible? (page 86)
Two theories, either it’s urine caused by incontinence or it’s due to Skene’s Glands.
9. Exactly what and where is the ‘G-spot’? My boyfriend and I can’t seem to find it! (page 87)
The G-spot is 1-2 inches into the vagina on the anterior wall.
10. I’ve heard that there is a new pill for women that works like Viagra for men. Is this true?
What does it do? (page 91)
‘Pink Viagra’ enhances female sexual response.
The physiology of sex is how our sexual structures function and produce our ability to respond
physically and emotionally to sexual stimulation. Anatomy and physiology are not the same. This
chapter evolves what happens to the body before during and after sexual activity, both solo and with a
partner, and explores physical changes that come with sexual desire, excitement, orgasm and
1
,Summary made by Car da Silva van der Meer - PSB3E-M20 Capita Selecta Human Sexology
resolution (returning to a non-aroused state), and classifies the similarities and differences in the
response of men and women.
Historical Perspective
Sexual Pioneers
A large portion of research on sexual behaviour prior to 1960 was done by Alfred Kinsley in the late
40s and 50s. His team surveyed thousands about their sexual behaviour and attitudes and reported on
a variety of topics, including frequency of intimacy and masturbation habits to homosexual
experiences. It has a lot of research about what people self-report, leaving a gap in how human bodily
function anatomically engaged in sexual activity.
William H. Masters and Virginia E. Johnson changed chat in the 60s. Their research on
human sexual physiology and response revealed to the world how our sexual bodies function during
sexual activity. This started the sexual revolution in the United States and the ‘free love’ movement.
This was an opportunity for candid and definitive scientific exploration of our sexuality that would
not have been possible before, as before sexual activity was seen as something to be quiet and
secretive about. To study the physiological response during sexual activity and stimulation, they
measured standard physiological responses such as pulse, blood pressure and rate of respiration, and
observed/recorded specific sexual responses. They recorded sexual activity with heterosexual couples
in different sex positions and during masturbation. Their book Human Sexual Response (1966) was
very important for many years to come. They later released more books, including Human Sexual
Inadequacy (1970), with both sexual dysfunctions and solutions, The Pleasure Bond (1974),
Homosexuality in Perspective (1979), Masters and Johnson on Sex and Human Loving (1986) and
Crisis: Heterosexual Behaviour in the Age of AIDS (1988). Their last book was Heterosexuality
(1994).
Biology, Psychology, and Human Sexual Responding
Though humans are animals, our sexual response is not solely governed by biological factors. Our
willingness to have sex is not clearly linked to a female's menstrual cycle. Psychology plays a role just
as great, if not greater, than biology in our sexual behaviour. Besides reproduction we may want to
have sex or masturbate to feel pleasure, give pleasure, experience intimacy, stress relief, feeling
valued by another, express value in another, feel more/less dominant/submissive and a myriad of other
reasons.
Masters and Johnson: the Excitement-Plateau-Orgasm-Resolution model
Like all researchers, Masters and Johnson made mistakes and thus not all conclusions are universally
accepted. Later in chapter 3 other theories on the sexual response cycle will be discussed. But for now,
Masters and Johnson created this one, involving 4 stages, Excitement, Plateau, Orgasm and
Resolution, or EPOR Model. It’s fundamentally impossible to know when excitement ends and where
the plateau begins, but the model was easy to understand.
Keep in mind sex is more than intercourse, and these can
occur during more than just intercourse, such as during oral,
masturbation or wet dreams.
Excitement
Involves early physical responses to any type of pleasurable
sexual stimulation. What triggers sexual arousal depends on
individual and cultural factors. Throughout history it’s
believed some chemicals, foods, drinks etc produce sexual
2
,Summary made by Car da Silva van der Meer - PSB3E-M20 Capita Selecta Human Sexology
desire in humans; aphrodisiacs. Science has yet to provide any evidence that true aphrodisiacs exist,
thus they remain a myth.
For both sexes, blood circulation increases to all erectile structures and causes them to expand
and stiffen; Vasocongestion. A sex flush, nipples become erect, breathing becomes heavier, heart rate
increases and voluntary muscles tense in a process called myotonia.
In men, one sign of sexual excitement is penile erection, tightening on scrotal skin and
testicles enlarging and risking up towards the underside of the penis. Erection may be lost if
stimulation is stopped or concentration wanders. Men may worry about loss of erection throughout the
sexual activity and this worry of (normal) fluctuation of penile erection may become a self-fulfilling
prophecy.
In women, the first sign of sexual excitement is vaginal lubrication and the clitoris becoming
erect. Internally the uterus engorges with blood and moves slightly upward in the abdomen, and may
exhibit fibrillation. The vagina becomes longer and widens out along the inner two-thirds of its length.
Breasts, nipples and areolas enlarge slightly (in both men and women).
Plateau
The plateau phase is when arousal seems to level off and remains at an elevated level of excitement.
All erectile tissue is engorged with blood. Respiration, heart rate, blood pressure and muscle tension
are all at high levels as orgasm approaches. In women, nipples remain erect and areolas continue to
become larger. The walls of the outer one-third of the vagina are engorged with blood and thickened,
reducing the size of the vaginal opening. This stimulates the penis during intercourse to ensure male
orgasm and ejaculation, but this occurs whether or not intercourse is taking place. The inner
two-thirds of the vagina continues to expand; Tenting. Tenting creates a place for semen to pool
directly under the cervix and stimulate it with hormones in seminal fluid to suck sperm into the uterus.
Clitoris continues to engorge and glands hide under the clitoral hood. Due to this, it’s less sensitive to
stimulation, and to reach orgasm during sexual intercourse there may be more stimulation needed.
This is why many women report other activities besides intercourse to be more satisfying. The labia
minora deepens in colour.
In men, the penis is fully erect and unlikely to be lost unless there is a major distraction.
Cornea enlarges and Cowper’s glands secreted pre-ejaculate fluid (‘pre-cum’). This fluid is to produce
additional lubrication for intercourse and may serve to flush out the urethra prior to ejaculation of
semen. It has live sperm cells and may have infection-causing microbes. The scrotal skin is tight, and
testicles are pulled close to the body.
Orgasm
The orgasmic phase only lasts about 15 seconds. Orgasms vary in characteristics and intensity from
person to person and depend on the sexual experience and how orgasm is achieved. Women tend to
require more stimulation than men to achieve orgasm with a partner; the majority of women do not
routinely experience orgasm through intercourse exclusively. Penile penetration may be pleasurable
but won’t generally lead to orgasm, and orgasm may not be the main motivation for intercourse for
women. Most require additional stimulation to the clitoral area before, during or after intercourse.
Orgasm is the result of direct or indirect stimulation of the clitoris, but due to the sensitivity of the
clitoris, direct stimulation may be too intense. Factors influencing the intensity and duration of orgasm
may be arousal prior to orgasm, time since the last orgasm, drug/alcohol use and level of
comfort/intimacy with a partner. Respiration increases dramatically, and pulse rate and blood pressure
continue to rise. Sexual flush spreads over the body. Loss of control of voluntary muscles causes
contraction and spasms. Muscles in the pelvic area contract at a rate of about 0.8 seconds.
3
, Summary made by Car da Silva van der Meer - PSB3E-M20 Capita Selecta Human Sexology
For women, the anus, uterus, pelvic floor muscles and walls of the outer third of the vagina
contact in intervals of 0.8 seconds, the number of contractions vary from 3 to 15.
For men, contraction of the anus and ejaculation. Ejaculation occurs in 2 stages; emission
(semen build-up in the urethral bulb, leads to a point of no return or Ejaculatory inevitability. After
emission, the prostate gland, urethra and muscles at the base of the penis contracts at intervals of 0.8
seconds) and expulsion (pushing semen through the urethra).
After orgasm, individuals are left in a stage of satisfied, warm sensations of emotional
well-being, aka the afterglow, facilitated by oxytocin.
Male and female descriptions of orgasms are very similar. Intercourse should be pleasure
directed instead of orgasms directed, as orgasm as the goal approaches leads to bland, repetitive and
non-intimate intercourse.
Variation in Orgasm
Though Masters and Johnsons claim women are capable of multiple orgasms and men pass through a
refractory period between orgasms, that conclusion is oversimplified. Men are capable of
experiencing multiple orgasms without loss of erection and ejaculation is not necessary with each
orgasm. However, documentation of multiple orgasms in men is small. Women who report multiple
orgasms during intercourse report similar levels of sexual satisfaction as women who report single
orgasms during sexual intercourse. Some women may orgasm multiple times during masturbation,
oral stimulation or vibrator use but only single during heterosexual intercourse.
Female Ejaculation and the “G-Spot”
The phenomenon of female ejaculation is subject to debate with two questions; do some women really
ejaculate upon orgasm and if so, what does female ejaculation consist of? Some claim the fluid
expelled by women upon orgasm is identical to urine, and some think it's more akin to semen. If it’s
urine, it may be due to contraction leading to incontinence (like how some people have stress
incontinence when laughing too hard). Several studies found that female ejaculation resembles male
prostatic fluid in chemical components, and women who report ejaculation do not appear more prone
to urinary stress incontinence.
Some assume fluid is secreted by two paraurethral glands known as Skene’s glands. They may
secrete fluid into the urethra at the moment of orgasm, though the purpose is unclear. As it is
expressed through the urethra and not the vagina it wouldn’t
significantly help lubrication. Women who ejaculate report
intense pleasure.
In the 80s a structure linked to the intensity of female
orgasm was ‘discovered’, by Ernst Grafenberg, thus named
Grafenberg spot or G-spot. The G-spot is located in the
anterior wall of the vagina about 1-2 inches from the vaginal
opening. It’s a slightly raised area about the size of a dime
during sexual stimulation. This spot is hard to find and thus
some researchers say it doesn’t exist. To find the G-spot,
place one or two fingers inside the vagina and press up
against the wall in a massaging motion. Some report that if
g-spot is stimulated during sexual activity, arousal and
orgasms are enhanced and intensified.
4
