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Chapter Four. Male Sexual Anatomy, Physiology, and Response. 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
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Chapter Four Male Sexual Anatomy, Physiology, and Response
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
External Structures • The penis • The scrotum
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
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: tube that transports urine and semen • When penis erect, urinary duct is blocked
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
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
Internal Structures • Testes: • Two major functions: sperm and hormone production • Shaped like olives • Size and weight decrease as men age • Not usually symmetrical • Suspended by spermatic cord • Within each testicle, there are Seminiferous tubules
Internal Structures • Epididymis • C shaped structure on the back of the teste • Vas Deferens • The ducts that carry sperm from testicles to urethra for ejaculation • Joins the ejaculatory duct within prostate gland
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
Other structures • Breasts • Anus • Buttocks • Rectum
Male Sexual Physiology • Production of hormones • Spermatogenesis
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
Spermatogenesis • Ongoing process starting at puberty • sperm produced within seminiferous tubules of testicles (64-72 days) • 20 days for sperm to travel through epididymis • Upon ejaculation, sperm expelled through urethra by muscular contractions
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
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