Arousal and Response Lighting the fire, Stoking the flame

Transcription

Arousal and Response Lighting the fire, Stoking the flame
Arousal and Response
Lighting the fire, Stoking the
flame
The Essential Hormones
• Two basic types – Steroid & Neuropeptide
• Steroid Hormones – secreted by the
gonads and adrenal glands
• Examples: testosterone, estrogen, etc.
• Not simply male or female – both sexes
produce each, but in varying amounts
Neuropeptide Hormones
• Produced in the brain, they influence
sexuality and behavior
• Perhaps the most significant:
• Oxytocin – the “love hormone”, it
influences our erotic and emotional bonds
Testosterone – “the motivator”
• Men have 20 to 40 times
•
•
•
more
Effects desire (libido) more
than function
But deficiencies do decrease
sensitivity and desire
Castration – the surgical
removal of the testes causes
dramatic reductions in sexual
interest and desire
Testosterone uses
Less Testosterone
• Antiandrogens – drugs which reduce
testosterone levels
• Occasionally given to sex offenders
• Usually decreases sexual interest and
activity
• But sometimes offenders assault for other
reasons , such as anger, power and
control
• Hypogonadism – testosterone deficiency
due to diseases of the endocrine system
• If it begins before puberty, development is
slowed
• If it starts after puberty, a marked
decrease in desire follows
Estrogens and Desire
• Their influence is undeniable but
exact role is unclear
• Research findings differ as to whether
they increase desire
Females & Testosterone
• Testosterone clearly increases female
sexual desire, sensitivity and activity
• True even for women after menopause or
removal of the ovaries
• Women with “normal” levels of sexual
activity and hormones who receive
additional testosterone show significant
increases in sexual arousal, sensation and
even lust
• Theresa Crenshaw “…. when a woman’s
testosterone dwindles, so does her sex
life.”
More On Testosterone
• Women have much less testosterone, but
are much more sensitive to its effects
• For women, too much testosterone causes
problems, such as “unwelcome” changes
to secondary sexual characteristics
• Women see levels fall more rapidly after
menopause than male’s more gradual
decline
• If measured, it is “free” (unattached)
testosterone that matters, not “total”
• Testosterone Replacement Therapy
commonly available for men
now, slowly becoming an option for
women
Marketing Testosterone
oxytocin
• A neuropeptide from the hypothalamus
that effects sexual response and attraction
• Bonding occurs through its release
mother/child – breast feeding
sexual partners – arousal and response
• Autistic children have low levels and
corresponding difficulties forming bonds
and expressing love
Oxytocin and Love
• Release is triggered by touch
• Its circulation increases the skins
sensitivity to touch
• Levels increase within us as we go
through the cycle of arousal to orgasm
• Presence remains in blood stream after
orgasm facilitating pair bonding
The Brain – Our Most Sexual
Organ?
• Our cerebral cortex stores memories and
images producing powerful fantasies
• Our culture has conditioned us to have
certain preferences for what we consider
physically attractive
• World-wide prototypes?
Exemplars of Beauty
• A 2005 poll of plastic surgeons revealed
the following as possessing the most
desired:
• Nose – Nicole Kidman
• Eyes – Catherine Zeta Jones
• Lips – Angelina Jolie
Nose
Eyes
Lips
The Limbic System
• A subcortical brain system of several
related structures that impact sexual
behavior
• Investigated through a number of studies
Olds (1950’s)
• Implanted electrodes in rat’s limbic system
• Allowed them to control stimulation
• When given the chance, rats will “dial their
own number” until they reach exhaustion,
even up to several thousand times an hour
• “pleasure centers”
Heath (1972)
• Humans with a variety of disorders were
allowed to self-stimulate their limbic
system
• One man pushed his button over 1500/hr,
described intense sexual pleasure, and
complained whenever a “session” ended
• A woman reported similar experiences,
even multiple orgasmic responses
The Hypothalamus
• Stimulation greatly arouses rats
• Its destruction crushes response
• Apparently, the medial preoptic area
(MPOA) is especially sensitive
• Heroin, morphine and other opiates
suppress activity of the MPOA
• Dopamine and testosterone excite it
Serotonin’s Influence
• Presence inhibits sexual activity
• Seems to have the opposite effects of
dopamine
• Released after males ejaculate and blocks
or dampens sensitivity to dopamine and
oxytocin
• SSRI’s have many negative effects on
sexuality
The Senses
• Many sources of erotic stimulation
• Their influence leads to tremendous
variety and amazing sexual
complexity
Touch
• Our nerve endings are unevenly
distributed, locations which are most
sexually responsive are called our
•
Primary Erogenous Zones, which
include our genitals, lips, buttocks, inner
thighs, neck, mouth, perineum
• But we find tremendous variability
• Secondary Erogenous Zones
other areas touched within the context of
sexual intimacy
• Could be anywhere on the body
• Established through classical conditioning?
Vision
• Very important in our society
• Emphasis on physical attractiveness,
grooming, clothes and cosmetics
• Are males more aroused by visual stimuli?
• Kinsey’s survey said, “YES!”
• But once women were presented with the:
1) right stimuli,
2) in the right settings, and
3) measured the right way,
STRONG similarities between men and
women were found
though women’s self-reports say no
Smell
• Are genitals smells arousing or awful?
• Depends largely on where you live
and your acceptance or rejection of
fragrance claims.
Pheromones
• Odors secreted by the body which relate
to reproduction
• Common for mammals
• The vomeronasal system relates to their
use
• Present in humans,
• But is it functional?
What Works
• Smells that arouse
• Women – licorice,
•
banana nut bread,
cucumbers
Men – lavender,
pumpkin pie,
doughnuts
What Doesn’t
• Women –
barbecued meat,
men’s cologne’s
• Men – Nothing
Aphrodisiacs
• Substances that
supposedly
increase sexual
desire and
capacity
Do They Deliver?
• Many claims – little evidence
• Alcohol, amphetamines, barbiturates,
cocaine and marijuana reduce inhibitions
but also sexual response
• The power of suggestion seems key
Hope on the Horizon?
• One substance,
yohimbine
hydrochloride (sap
of the tropical
evergreen) does
increase desire and
performance
Anaphrodisiacs
• Substances which inhibit sexual desire
and performance
• Many things “work”
• Drugs such as opiates, tranquilizers, and
antidepressants inhibit ejaculation and
cause erectile problems in males and
decrease orgasmic capacity for females
Other Anaphrodisiacs
• Birth control pills decrease free
testosterone levels
• Nicotine both decreases vasocongestion
and reduces testosterone levels
Sexual Response
• A highly individualized process
• Research has revealed common
patterns of physiological changes
Kaplan’s Three Stages
• Desire – a prelude to physical sexual
response, ignored by Masters and Johnson
• Excitement
• Organism
• Masters and
Johnson
• Sexology
Trailblazers
• Direct
Observation
Masters and Johnson’s Four
Phases
• Excitement
both men and women:
muscle tension, anatonia
increased heart rate/blood pressure
engorgement
sex flush
More Excitement
• Women:
engorgement
lubrication
enlargement
• Men:
erection
enlargement/elevation
Stage II - Plateau
• The acceleration of processes begun in the
excitement phase
• Females
the orgasmic platform – the
significantly engorged outer 1/3 of the
vagina
• Lasts from a few seconds to a few minutes
Phase III - Orgasm
• Involuntary muscle spasms
• Blood pressure, respirations, heart
rate peaks
• Males – emission then expulsion
• Are the males’ and females’
experiences different ?
• Descriptions are indistinguishable.
Are some Orgasms superior ?
• Freud thought so, claiming that vaginal
orgasms are more “mature” than clitoral
• This view, influential for decades, has
been abandoned
• Masters and Johnson established that
there is just one kind of female orgasm,
though most arise from clitoral stimulation
Return to the “G” Spot
• Once found, manual stimulation produces
variable sensations
• Intense pleasure and orgasm usually
follows
• Some women even experience ejaculation
• But the source of the fluid is uncertain
Finally, Resolution
• Process through which sexual systems
return to a nonexcited state
• While in most respects the sexes
experience this process similarly, men go
through a refractory period during which
they cannot experience another orgasm
Aging and the Response Cycle
• Function continues but intensity declines
• Older women – longer for lubrication
Occasional decreases in desire,
sensitivity, and capacity
• Older men – longer for erection/orgasm
greater control
longer refractory period
Where the Sexes Differ
• Despite surprising similarities, some
distinctions remain
• Variability
Women have three patterns within the
sexual response cycle
Men just one
The Male Refractory Period
• Why?
• Evolution based ? Give another guy a
chance ?
• Dependent on midbrain-
hypothalamus pathway ?
Multiple Orgasms
• Women can have several, in succession
• But just 14 to 16% ?
• Masters and Johnson say most can have
5-6 !
• Men can too ?!?