Chapter Four
Male Sexual Anatomy,
Physiology, and Response
HESS 503 Human Sexuality
Male Sex Organs:
What Are They for?
 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

HESS 503 Human Sexuality
External Structures

The penis

The scrotum
HESS 503 Human Sexuality
External Male Sexual Structures
Circumcised vs. Intact Penis
HESS 503 Human Sexuality
The Penis

Penis: from Latin word for tail
 organ

through which sperm and urine pass
Three main sections:
 Root:
attaches penis within the pelvic cavity
 Shaft: contains 3 parallel columns of erectile tissue


Corpora cavernosa: 2 columns along the front surface
Corpus spongiosum: runs beneath corpora cavernosa, also
forms the glans
HESS 503 Human Sexuality
Cross section – shaft of penis
Anterior View
HESS 503 Human Sexuality
The Penis
 Glans
penis: head of penis; most sensitive
 Corona: rim at base of the glans
 Frenulum: on underside of penis; triangle of
sensitive skin
 Foreskin: sleeve-like covering of the glans
 Circumcision
 Urethra: a tube that transports urine and semen
 When penis erect, urinary duct is blocked
HESS 503 Human Sexuality
The Penis: Myths
Penis size not linked to body size or
weight, muscular structure, race or
ethnicity or sexual orientation
 No relationship between penis size and
ability to have sexual intercourse or satisfy
a partner

HESS 503 Human Sexuality
The Scrotum
A pouch of skin that holds the two testicles
 Scrotum skin more heavily pigmented
 Sparsely covered with hair
 Divided in the middle by a ridge of skin
 Testicle temperature control: 93°F

HESS 503 Human Sexuality
Internal Structures

Testes:
 Two
major functions: sperm and hormone
production
 Shaped like olives; 1.5” long and 1” diameter.
 Size and weight decrease as men age
 Not usually symmetrical in the way they hang
 Suspended by spermatic cord
 Within each testicle, there are about 1000
Seminiferous tubules: Production of sperm takes
place in these tubes
HESS 503 Human Sexuality
Internal Lateral View of Male Sex
Organs
HESS 503 Human Sexuality
Internal Structures

Epididymis
C
shaped structure on the back of the teste
 Sperm mature in epididymis

Vas Deferens
 The
ducts that carry sperm from testicles to
urethra for ejaculation
 Vas deferens joins the ejaculatory duct within
prostate gland
HESS 503 Human Sexuality
Internal Lateral View of Male Sex
Organs
HESS 503 Human Sexuality
Cross section – Epididymis, Vas
deferens
HESS 503 Human Sexuality
Internal Structures

Seminal vesicles
 Secrete

fluid that makes up 60% of semen
Prostate gland
 Secretes
fluid that makes up 30-35% of semen
 Can be stimulated in anal play

Cowper’s (bulbourethral) glands
 Secrete

thick clear mucus prior to ejaculation
Urethra
HESS 503 Human Sexuality
Internal Lateral View of Male Sex
Organs
HESS 503 Human Sexuality
HESS 503 Human Sexuality
Other structures
Breasts
 Anus
 Buttocks
 Rectum

HESS 503 Human Sexuality
Male Sexual Physiology
Production of hormones
 Spermatogenesis

HESS 503 Human Sexuality
Male Reproductive Hormones

Testosterone
 Acts
on seminiferous tubules to produce
sperm
 Regulates sex drive
 Is responsible for development of secondary
sex characteristics in puberty
 Influences growth of bones and muscle mass
HESS 503 Human Sexuality
Hormone Regulation
HESS 503 Human Sexuality
Male Reproductive Hormones
HESS 503 Human Sexuality
Spermatogenesis

Ongoing process from puberty onward
 Sperm
produced within seminiferous tubules
of testicles (64-72 days)

Several 100 million sperm produced daily
 20
days for sperm to travel through
epididymis

During this time they become fertile and motile
 Upon
ejaculation, sperm expelled through
urethra by muscular contractions
HESS 503 Human Sexuality
Spermatogenesis
HESS 503 Human Sexuality
Mature Spermatocyte
HESS 503 Human Sexuality
Male Sexual Response

Erection
 Blood
vessels expand and increase blood in
penis
 Veins that normally carry blood out are
compressed, leading to engorgement of penis
 Secretions from Cowper’s glands appear at
tip
HESS 503 Human Sexuality
HESS 503 Human Sexuality
Ejaculation and Orgasm

Emission stage
 Sperm
sent into vas deferens
 Rhythmic contractions begin
 Feeling of ejaculatory inevitability

Expulsion stage
 Rapid
contractions
 Semen spurts from urethral opening

Orgasm
 Intensely
pleasurable physical sensations that
usually accompany ejaculation
 Followed by refractory period
HESS 503 Human Sexuality
HESS 503 Human Sexuality