HUMAN SEXUALITY

Chapter Six: Sexual Arousal and Response

The Role of Hormones in Sexual arousal

The Brain and Sexual Arousal

The Senses and Sexual Arousal

Aphrodisiacs and Anaphrodisiacs in Sexual Arousal

Sexual Response

Aging and the Sexual Response Cycle

Some Differences Between the Sexes in Sexual Response

testosterone is linked to male sexual desire (libido)

castration/orchidectomy

leads to decreased sexual interest and activity

antiandrogens reduce sexual interest and activity (M & F)

example:medroxyprogesterone acetate (MPA, Depo-Provera)

hypogonadism

a state of testosterone deficiency

results from certain endocrine diseases

linked to decreased sexual interest

may be normalized with testosterone replacement therapy

testosterone is linked to female sexual desire (libido)

role of estrogens

in female sexual motivation and functioning

remains unclear

in females there is evidence of

a clear causal relationship

between levels of circulating testosterone

and sexual desire,

genital sensitivity,

and frequency of sexual activity

[picture of adrenal glands, testicles, and ovaries]

The Invision Guide to Sexual Health p.23

Text by Elizabeth R. Boskey, Ph.D., M.P.H.

Male total testosterone 300-1200 ng/dl

free testosterone 1.0 - 5.0 ng/dl

Female total testosterone 20-50 ng/dl

free testosterone 0.1 - 0.5 ng/dl

the essential amount (“critical mass”) of testosterone necessary for adequate functioning

varies from person to person

within both sexes

signs of testosterone deficiency

decrease

desire

sensitivity - genitals and nipples

arousability

energy levels / depressed mood

bone mineral density

body hair

muscle mass & strength

increase

fat mass

testosterone-replacement therapy

testosterone supplements (for men or women)

orally (swallowing)

sublingually (under-the-tongue tablets)

injection

implantation of a pellet

transdermal skin patch

oxytocin – “cuddle hormone”

promotes a feeling of connection, bonding

released when we hug spouses or children

released when mother nurses infant

released at orgasm

treating autistic people with oxytocin

sometimes helps alleviate symptoms

treating female animals with oxytocin makes

them act maternal

[picture of prairie voles and cartoon of meadow voles]

the prairie vole mates for life

asocial promiscuous meadow vole being converted to living monogamous

by insertion of V1a receptor gene

British Society for Neuroendocrinology

The Neurobiology of Social Bonds

Professor Keith M Hendrick

The Babraham Institute Cambridge

http://neuroendo.org.uk/index.php/content/view/34/11/

American Scientist Online

High on Fidelity:

What can voles teach us about momogamy?

Marla Vacek Broadfoot

http://www.americanscientist.org/template/

AssetDetail/assetid/14756?&print=yes

[drawings of brains showing how the insertion of a gene for expressing more receptors

causes the same amount of oxytocin or vasopressin to result in a greater release of

dopamine and more pleasure]

the brain and sexual arousal

strictly mental events

(such as fantasies)

are the product of the cerebral cortex

[the thin outer layer of the brain]

the brain and sexual arousal

direct electrical stimulation

in certain areas within the limbic system

results in sexual pleasure & multiple orgasms

the limbic system is a region of the brain

associated with emotion and motivation

functional MRI

woman bringing herself to orgasm

through thought and fantasy alone

The Invision Guide to Sexual Health p.32

Text by Elizabeth R. Boskey, Ph.D., M.P.H.

the senses and sexual arousal

touch: primary erogenous zones

-locations most responsive to tactile stimulation

because of dense concentrations of nerve endings

(genitals, buttocks, anus, perineum, breasts, inner thighs, armpits, navel, neck, ears, mouth)

secondary erogenous zones

-other locations of the body

that have become endowed with erotic significance

through sexual conditioning

two-point discrimination

average minimal distance where two points are still felt:

tongue = 1 mm, fingertip = 2-3 mm, palm = 1 cm, back = 4-7 cm

Rapid Access Guide To the Physical Examination

Donald W. Novey

Page 495

If the area of each body part was proportionate to its sensitivity

people would look very different.

Mapping the Mind

p75

the senses and sexual arousal

vision

smell

taste

hearing

aphrodisiac

a substance that allegedly

arouses sexual desire

and increases the capacity for sexual activity

oysters, bananas, celery, cucumbers

tomatoes, ginseng root, potatoes

ground-up horns of animals such as rhinoceros and reindeer

alcohol, amphetamines, barbiturates

cantharides (“Spanish fly”),cocaine

LSD and other psychedelic drugs, marijuana

amyl nitrite (“poppers”), L-dopa, yohimbine, Libido

anaphrodisiac

a substance that inhibits sexual desire and behavior

opiates (such as heroin, morphine, and methadone)

tranquilizers, antihypertensives,

antidepressants, antipsychotics

nicotine, birth control pills, progesterone

sedatives, ulcer drugs, appetite suppressants,

steroids, anticonvulsants

over-the-counter allergy medicines that cause drowsiness

drugs for treating cancer, heart disease, fluid retention

fungus infections

alcohol and sex

alcohol is not a stimulant

but a depressant of the brain

alcohol reduces cortical inhibitions such as fear and guilt

with increased levels of intoxication,

both men and women experience:

reduced sexual arousal (as measured physiologically)

decreased pleasurability and intensity of orgasm

increased difficulty in attaining orgasm

alcohol and sex

research has demonstrated a strong association

between the use of alcohol

and an inclination to participate in

high risk sexual practices (risk of AIDS etc)

Masters and Johnson’s model

of the sexual response cycle

(female)

excitement

plateau

orgasm

resolution

(male)

excitement

plateau

orgasm

refractory period

resolution

Helen Singer Kaplan model of sexual response

desire

excitement

orgasm

three basic patterns in female sexual response

identified by Masters and Johnson

only one male response pattern

identified by Masters and Johnson

two fundamental physiological responses

to effective sexual stimulation occur in both women and men

vasocongestion = the engorgement of blood vessels in particular body parts in response to sexual arousal

myotonia = muscle tension

p. 102 FOR WOMEN ONLY:

A Revolutionary Guide to Overcoming Sexual Dysfunction

and Reclaiming Your Sex Life.

excitement phase

duration: less than a minute – several hours

engorgement

penis, testes

clitoris, labia minora, vagina, nipples

sex flush

increased muscle tension

increased heart rate and blood pressure

production of vaginal lubrication

plateau phase

duration: a few seconds - several minutes

heart rate, blood pressure, breathing rates increase

sex flushes, genital coloration more noticeable

muscle tension increases

involuntary contractions and spasms (face, neck, hands, feet)

markedly increased engorgement - outer third of vagina

clitoris withdraws under hood

Cowper’s gland secretes

orgasm phase

duration: a few seconds

series of muscular contractions of pelvic floor muscles

occurring at peak sexual arousal

male emission phase - seminal fluid gathered in urethral bulb

(sense that orgasm is inevitable)

male expulsion phase - semen expelled out of penis

female - uterine contractions

resolution phase

if no additional stimulation occurs

resolution begins immediately after orgasm

all sexual systems return to nonexcited state

some changes take place rapidly, others more slowly

after orgasm, the male typically enters a

refractory period

a time when no amount of additional stimulation

will result in orgasm

duration: minutes - days

factors affecting duration:

age

frequency of previous sexual activity

degree of emotional closeness to partner

women generally experience

no comparable refractory period

they are physiologically capable

of returning to another orgasmic peak

from anywhere in the resolution phase

Grafenberg Spot (G spot)

area of erotic sensitivity

along anterior wall of the vagina

stimulation may result intense orgasm

sometimes accompanied by ejaculation (from urethra)

female ejaculate has components similar to prostate secretions

[picture based on MRIs showing clitoris & G-spot]

The Invision Guide to Sexual Health p.37

Text by Elizabeth R. Boskey, Ph.D., M.P.H.

according to Freud

clitoral orgasm - immature stage of sexuality

vaginal orgasm - mature stage of sexuality

sexual response cycle of older women

vaginal lubrication

may begin more slowly

amount may be reduced

vaginal mucosa - thinner and lighter colored

number of contractions at orgasm may decrease

orgasmic contractions may be painful

resolution typically occurs more rapidly

sexual response cycle of older men

penile erection takes minutes instead of seconds

may require more direct (manual or oral) stimulation

plateau phase may last much longer

number of contractions at orgasm may decrease

resolution typically more rapid

refractory period lengthens to hours or even days

differences between male and female sexual response

greater variability in female response

Masters and Johnson recognized three patterns

of sexual response in females, one in males

the male refractory period

no comparable period in women

multiple orgasms

both women and men have had multiple orgasms

under laboratory conditions

greater percentage of women (vs. men)

have experienced multiple orgasms