Human Sexuality NSG 3403

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Human SexualityNSG 3403

• Male
• Anatomy Physiology
• Sexual Response

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Male Anatomy Physiology

• External Structures
• Penis
• Root
• Shaft
• Head glans
• corona
• frenulum
• foreskin (prepuce) - uncircumcised/circumcised
• smegma
• Nerves, blood vessels, fibrous tissue

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Male Anatomy Physiology

• Shaft of penis
• 3 parallel columns of erectile tissue
• (no muscle, no bone)
• 2 corpora cavernosa (top front surface)
• 1 corpus spongiosum (underside)
• urethra
• When aroused fills with blood (vasocongestion)
  expand.
• Unaroused penis
• Aroused penis more uniform sizes
• Pelvic muscles - Kegel exercises

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Male Anatomy Physiology

• Factors effecting size
• heredity, vasocongestion, cold air or water,
  fear, anxiety (penis draws closer to body
  smaller size)
• Erection urethra/urinary duct closes so semen
  passes through (ejaculation)
• Erection not always because of sexual excitement
• REM sleep (dreaming)

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Myths

• Penis Size related to masculinity, aggression,
  ability to perform, sexual attractiveness,
  virility.
• Size of shoe predictive of penis size (not
  research based!).
• Size not related to ability to have sexual
  intercourse or pleasure partner.
• Small flaccid penis enlarges more with erection
  than larger flaccid penis.

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• My brain is my second favorite organ!
• Woody Allen

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External Structures

• Scrotum Sac or pouch of skin, hangs from root
  of penis, holds 2 testicles in separate chambers.
• Skin is heavily pigmented, sparse hair, ridge of
  skin in middle which divides the scrotal sac.
• Skin changes aroused or cold (testes close to
  body skin wrinkled - compact)
• Protects testes, maintain temp. _at_ 93 F.

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Internal Structures

• Testes - testicles, gonads
• Function - Sperm production Hormones
• Size 1.5 X 1 diameter, 1 ounce
• Left usually hangs lower than Right ?
  size with aging
• In scrotum, testicles suspended by spermatic
  cord, with nerves, blood vessels vas deferens
  (tube carries sperm from testes)
• In testes 1000 Seminferous tubules - tiny tight
  compressed tubes 1-3 ft. where spermatogenesis
  (sperm production) occurs
• Fetus - testes grow inside pelvis, descend to
  scrotum near birth (sometimes not until 1-2 yrs
  old).

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Internal Structures

• Epididymis - where seminiferous tubules merge,
  sperm mature, stored. Shaped like comma,
  coiled tubes of 20.
• Merge with vas deferens (18tubes from abd.
  cavity over bladder joining with ejaculatory duct
  in the prostate, opening into urethra. (Can feel
  the vas deferens in scrotum is tube cut with
  vasectomy for sterilization doesnt effect
  erection or sexual performance

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Internal Structures

• Seminal Vesicles - 2 glands behind prostate
  gland, size shape of finger, secretes fluid
  60-70 of seminal fluid (nourish energize
  sperm)
• Prostate Gland - surround urethra below bladder,
  muscular gland, size shape of chestnut
  produces 30-35 seminal fld. (alkaline to protect
  sperm)
• Cowpers Glands - below prostate, 2 pea-sized
  glands connect to urethra by ducts secrete
  thick, clear mucus before ejaculation (at tip of
  penis) alkaline to protect sperm from acidic
  vagina. Fluid has sperm!
• (Sperm in urethra PREGNANT!!)

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Other Structures

• Breasts of Male (gynecomastia)
• Urethra
• Buttocks

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Male Hormones

• Hormones in testes (Leydig cells) secrete
  Androgens (male hormone)
• Testosterone triggers sperm, regulates sex
  drive, sexual desire (dominant hormone in males)
• Inhibin - testes regulates sperm production
• Relaxin - prostate increases sperm motility

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Male Hormones

• Male Cycle
• Many similarities to female cycle
• Mood changes behavior patterns
• Not sure if testosterone levels change to cause
  cycles, and not as dramatic as female cycles tend
  to be.
• Testosterone levels lowest at 8 PM highest at
• 4 AM, Lowest in spring, higher in fall.

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Male Hormones

• Spermatogenesis
• several hundred million sperm produced in
  seminiferous tubules. Takes 64-72 days
  epididymis for maturing 20 days to become
  fertile motile
• Ejaculation sperm _at_ end of epididymis by
  muscle contractions into vas deferens urethra
  mixes with sperm expelled from urethra

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Reproductive Process

• Fertilization of ovum (egg) - zygote has X
  chromosome
• Sperm determines sex of zygote
• If sperm has X chromosome Its a girl!
  (XX)
• If sperm has Y chromosome Its a boy!
• (XY)
• Sometimes various combos cause sexual
  development to be different (later discussion)

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Reproductive Process

• Semen production
• Seminal Fluid - ejaculated liquid with sperm
• Function nourish sperm, hospitable environment,
  transportation of sperm
• Is combo of seminal vesicle fld., prostate
  gland fld., sperm mixed in the urethra during
  ejaculation.

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Reproductive Process

• Semen
• Is thick sticky (clotting factor in fluid)
• Keeps the sperm together during transport
• then liquefies so sperm can swim out.
• Color varies opalescent (milky white), yellowish
  or grayish as ejaculate, then becomes clear as it
  liquefies.
• 1 tsp. (2-6 Milliliters) semen ejaculated
  200500 million sperm
• (p. 125 in text)

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Reproductive Process

• Sperm
• Head
• Midpiece
• Tail
• Head of sperm resembles penis
• Motility by tail of sperm
• X Y chromosome in head (nucleus)

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Part 2
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Human SexualityNSG 3403

• Male Sexual Response
• Part 2

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Sexual Arousal

• Hormones
• Testosterone (Androgen - Male Hormones, females
  also) produced by testes, adrenal glands,
  ovaries
• Estrogen - female hormone, produced by testes
• Free testosterone influences libido
• critical mass - amount varies, excess
  testosterone can harm M F

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Sexual Arousal

• Brain -
• cerebral cortex - how we think about sex
• limbic system - how we feel about sex, how we
  behave sexually
• hypothalamus - stimulation triggers arousal
  orgasm

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Sexual Arousal

• The senses
• Touch - dominant sexual sense
• Primary erogenous zones
• Secondary erogenous zones
• Vision - next most important sense
• Smell - may arouse or offend
• Pheromones
• Taste - minor role for most
• Hearing - varies

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Male Sexual Response

• Similar process for male as female except ?
• 1. Male fully aroused ready for penetration
  in less time than female
• 2. Orgasm for male usually have longer
  refractory/recovery time before next orgasm
  females can experience multiple orgasms.

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Male Sexual Response

• Arousal includes
• myotonia - muscle contractions, ? muscle tension
• vasocongestion - ?blood, engorged tissue
  erection of penis being the most obvious

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Response Cycles

• Kaplan
• Desire
• Distinct (not required)
• Excitement
• Orgasm

• Masters Johnsons
• Excitement Phase Vasocongestion, myotonia, flush
• Plateau Phase
• Orgasm Phase
• Resolution Phase
• Refractory period

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The Process

• 1. Erection
• aroused, ?blood into penis, vessels expand,
  corpora cavernosa corpus spongiosum fill
  expand penis erect compression of vessels
  prevents blood flow out of penis Engorgement
  Cowpers glands secretions at tip of penis.

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The Process

• 2. Ejaculation Orgasm
• stimulation of penis ejaculation (semen
  expelled from urethra) Spinal reflex triggers
  nerve impulses to ducts, glands, muscles of
  reproductive system.

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The Process

• Emission Stage -
• epididymis contract, sperm vas deferens,
  rhythmic contractions in seminal vesicles
  ampullae ejaculatory ducts dump to urethra
• Bladder sphincter closes, prostate sphincter
  closes
• Sensation experienced Ejaculatory
  Inevitability
• ? Heart rate, ?BP, ? respirations, ?muscle
  tension, sex flush (25)

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The Process

• Expulsion Stage -
• rapid, rhythmic contractions urethra, prostate,
  muscles of base of penis
• 1st most forceful semen spurt through urethral
  opening intensity ?, interval ?, heart, Blood
  Pressure, respirations ?

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The Process

• Orgasm
• Intense, pleasurable physical sensations
  general release of tension accompanying
  ejaculation.
• Does not always occur with ejaculation
• Ejaculation not always occur with orgasm
• Refractory Period - no erections/orgasms for
  varying time (factors age, environment,
  individual)
• few minutes to few days - maybe chemical effects
  in brain (text p. 184)

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The Process

• After orgasm blood flow ? , erection ?, sex
  flush ?, perspiration ?.
• Blue Balls
• Intense arousal without orgasm heaviness felt
  in testes. Not as painful as implied.
• If discomfort continues - masturbation
  ejaculate for release.

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More info

• When seminal vesicles are full, feedback signals
  to ?sperm (inhibin) production.
• Extra sperm die and are absorbed by body

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More Info

• Dry orgasm - young boys or prior to final
  ejaculation with intercourse
• Retrograde Ejaculation - backward into bladder,
  sphincter not closed, temporary (related to meds)
  or persist
• Ordinarily is not harmful
• Semen is eliminated by the body with urinating
• Nocturnal emissions wet dreams - involuntary
  ejaculation during sleep

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Any Questions?