HUMAN SEXUALITYDiversity in Contemporary AmericaFIFTH EDITION

Bryan Strong Christine DeVault Barbara W. Sayad William L. Yarber

C h a p t e r

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3Female Sexual Anatomy

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2 Female Sex Organs• All embryos appear as female at first

– Genetic and hormonal signals trigger the development of male organs in those embryos with XY chromosomes that will become male

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3 Female Sex Organs in Utero

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4 Female Sex Organs• In spite of all that is known about

female sex organs, some anatomical questions remain unknown or disputed– Range in clitoral size– Existence and function of the G-spot– Placement of nerves in the pelvic cavity

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5 Female Sex Organs• Sex organs serve a reproductive

function• Also serve other functions:

– Bringing pleasure to self– Giving pleasure to others– May serve to attract potential sexual

partners– Sharing of genital sexuality can play a

bonding role in relationships

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6 External Structures• External female genitals:

– mons pubis– clitoris– labia majora– labia minora

• These genitals are collectively known as the vulva– Often referred to as “vagina,” yet the vagina is

an internal structure

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7 External Structures

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8 Mons Pubis• Latin for “pubic mound:”

– The pad of fatty tissue that covers the area of the pubic bone about 6” below navel.

– Pubic hair grows on mons pubis beginning in puberty

– In many women, this area is sensitive to stimulation

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9 Clitoris• The Clitoris is the center of sexual

arousal in the female– Contains a high concentration of nerve

endings– Exquisitely sensitive to stimulation

• glans clitoris: the shaft of the clitoris• Clitoral hood: covers glans when clitoris not

engorged– Structurally analogous to penis, though

sole function of the clitoris is sexual arousal

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10 Clitoris• Clitoris also has an internal structure

– Two 3.5” long branches called crura– crura contain two corpora cavernosa: hollow

chambers that fill with blood and swell during arousal

• The clitoris when stimulated– Enlarges initially, then retracts beneath hood

just before and during orgasm– Follows same pattern with repeated orgasms,

though swelling is less pronounced

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11 Labia Majora and Minora• Labia Majora

– Two folds of spongy flesh extending from the mons pubis and enclosing the labia minora, clitoris, urethral opening, and vaginal entrance

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12 Labia Majora and Minora• Labia Minora

– Small folds within the labia majora that meet above the clitoris to form the clitoral hood

– They vary in appearance from woman to woman

– They are sensitive to the touch and swell during sexual arousal

– They enclose the “vestibule:” the vaginal opening

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13External genitals during sexual arousal• Clitoris becomes erect• Labia minora widen• Vestibule (vaginal opening) becomes

visible• Bartholin’s glans (located in the

vestibule) secrete small amount of moisture

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14 Internal Structures• Vagina: from Latin word for sheath

– Two reproductive functions:• Encompasses penis during coitus (vaginal intercourse)• Birth canal

• Introitus: the lower third of the vagina– The majority of the vagina’s nerve endings are

there• Hymen: named for Roman god of marriage

– a thin membrane that partially covers introitus prior to first intercourse or other insertion

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15 Internal Structures

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16 Internal Structures• Grafenberg Spot (G-spot)

– An erotically sensitive area on front wall of the vagina mid-way between pubic bone and cervix

– Existence somewhat controversial• Uterus: a hollow, thick-walled muscular organ

– Accommodates developing fetus during pregnancy– Only 3” by 3” in women who have not given birth– Inner lining of uterine walls known as endometrium

• Cervix: the tapered end of the uterus, extends and opens into the vagina– Secretes mucous; menstrual fluid travels through

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17 Internal Structures

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18 Internal Structures• Ovaries: gonads that produce gametes

– Produce egg cells (oocytes; ova) for reproduction

– Two ovaries; size and shape of large almonds– Ovaries release oocytes in a process called

ovulation• Fallopian tubes:

– Also known as uterine tubes of oviducts– One tube extends toward each ovary– They fan over the ovaries, and carry oocytes

into the uterus during ovulation

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19 Other Structures• Urethra: tube through which urine

passes• Urethral opening• Perineum: area between genitals

and anus• Pelvic floor

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20 Other Structures• Anus: opening of rectum

– Contains two sphincters (circular muscles that open and close like valves)

– Some women and men find that the tissue of the anus is erotically sensitive

– The lining of the rectum is fragile• if engaging in anal sex play care must be

taken not to rupture the delicate tissues

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21 Other Structures• Breasts: both women and men have

them• Reproductive function of female breasts is

to nourish offspring through lactation• Composed of fatty tissue and 15-25 lobes

that radiate around a central nipple•Areola: the ring of darkened skin around

nipple• Nipples get erect in response to touch, cold,

or sexual arousal– Many (not all) women find breast

stimulation pleasurable.

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22 Other Structures: Breasts

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23Female Sexual Physiology: Reproductive Hormones• Hormones: chemical substances

that serve as messengers– Gonadotropins act directly on gonads

• Estrogens: affect maturation of reproductive organs, menstruation, and pregnancy

• Progesterone: helps maintain the uterine lining

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24Female Sexual Physiology: Reproductive HormonesHormone Where Found FunctionsEstrogen ovaries, adrenal glands,

placenta during pregnancy

Promotes maturation of reproductive organs, development during puberty, regulates menstrual cycle, pregnancy

Progesterone ovaries, adrenal glands Promotes breast development, maintains uterine lining, regulates menstrual cycle, sustains pregnancy

Gonadotropin-releasing hormone (GnRH)

hypothalamus Promotes maturation of gonads, regulates menstrual cycle

Follicle-stimulating hormone (FSH)

pituitary Regulates ovarian function and maturation of ovarian follicles

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25Female Sexual Physiology: Reproductive Hormones

Hormone Where Found FunctionsLuteinizing hormone (LH)

pituitary Assists in production of estrogen and progesterone, regulates maturation of ovarian follicles, triggers ovulation

Human chorionic gonadotropin (HCG)

embryo and placenta Helps sustain pregnancy

Testosterone adrenal glands and ovaries

Helps stimulate sexual interest

Oxytocin hypothalamus stimulates uterine contractions in childbirth

Prolactin pituitary stimulates milk production

Prostaglandins all body cells mediate hormone response, stimulate muscle contractions

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26Female Sexual Physiology: The Ovarian Cycle• Cycle averages 28 days

– Normal women’s cycles last between 21 & 40 days

– Generally occurs in only one ovary per month

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27 The Ovarian Cycle

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28 The Ovarian Cycle• 3 Phases:

– Follicular phase: Days 1-10• Hormones signal 10 to 20 follicles to grow

on ovaries; Estrogen matures one oocyte– Ovulatory phase: Days 11-14

• Oocyte undergoes cell division; Follicle wall thins and ruptures; oocyte enters abdominal cavity near fimbrae of fallopian tube

– Luteal phase: Days 14-28• Estrogen levels drop; egg travels through

fallopian tube towards uterus

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29The Ovarian Cycle: Follicular Phase

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30The Ovarian Cycle: Ovulatory Phase

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31The Ovarian Cycle: Luteal Phase

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32 Menstruation

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33 The Menstrual Cycle• 3 Phases:

– Menstrual phase (about 3-5 days)• Endometrium is shed• Endometrial tissue, mucous, other secretions, and

2-5 oz. Blood is expelled through vagina– Proliferative phase (about 9 days)

• Endometrium thickens, clear thin mucus secreted• Ends with ovulation

– Secretory phase (14 days)• endometrium prepares for arrival of fertilized

ovum• If no fertilization, ends with shedding of

endometrium

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34 Menstrual Effects• Emotional, physical, or behavioral

changes – The vast majority of women notice in the week

prior to menstruation– More severe symptoms are associated with Pre-

Menstrual Syndrome (PMS)• Dysmenorrhea

– pelvic cramping and pain during menstruation– Caused by prostaglandins, a type of hormone

• Amenorrhea – absence of menstruation for reasons other than

aging

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35Female Sexual Response Models• Masters & Johnson 4 Phase Model:

– excitement– plateau– orgasm– resolution

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36Female Sexual Response Models• Kaplan’s Tri-Phasic Model

– Desire– Excitement– Orgasm

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37Female Sexual Response Models• Loulan’s Sexual Response Model:

– Incorporates biological & affective dimensions• Willingness• Desire• Excitement• Engorgement• Orgasm• Pleasure

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38 Desire: Mind or Matter?• Desire is the psychological

component of sexual arousal.– A complex interaction between

• Thoughts and feelings• Sensory organs• Neural responses• Hormonal reactions

– Occurs throughout many parts of the body

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39 Women’s Sexual Excitement• Sweating: moistening of vaginal walls• Tenting: inner 2/3 of vagina expands• Labia may enlarge or flatten & separate• Clitoris swells• Breathing and heart rate increase• Nipples become erect, breasts may

enlarge• Uterus elevates

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40 Women’s Sexual Excitement• As excitement increases

– Clitoris retracts beneath clitoral hood– Vaginal opening decreases by about 1/3– Outer third of vagina becomes more

congested, forming the orgasmic platform.

• Continued stimulation brings orgasm:– Rhythmic contractions of the vagina,

uterus, and pelvic muscles accompanied by pleasurable sensation.