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Male Sexual Anatomy, Physiology, and Response

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Title: Male Sexual Anatomy, Physiology, and Response


1
Male Sexual Anatomy, Physiology, and Response
2
Male 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

3
External Structures
  • Penis, Scrotum

4
The Penis
  • Penis from Latin word for tail
  • organ through which sperm and urine pass
  • Contains urethra for urine and semen transport
  • Becomes erect to better penetrate the vagina and
    deposit sperm near the os
  • No bone, little muscle

5
The Penis
  • Myths about the penis abound
  • Penis size not linked to body size or weight,
    muscular structure, race or ethnicity or sexual
    orientation. Determined by heredity.
  • No relationship between penis size and ability to
    have sexual intercourse or satisfy a partner.

6
The Penis
  • Three main sections
  • Root attaches penis within the pelvic cavity
  • Shaft body of the penis (hangs free)
  • 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

7
The Root of the Penis
  • Extends into the body below the pubic bone
  • Attached to internal pelvic muscles and can be
    felt in the perineum

8
  • Figure 6.1 The internal structure of the penis.

9
The Penis Cross-Section of the Shaft
10
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 attaches glans to foreskin.

11
The Penis
  • Foreskin sleeve-like covering of the glans
  • Often surgically removed in infancy circumcision
  • Crura (pl.) formed by the corpora cavernosa
    anchored by muscle to public bone
  • Urethra a tube that transports urine semen
  • Runs from bladder through penis. Opens at tip of
    glans.
  • When penis erect, urinary duct is blocked

12
  • Figure 6.2 The male reproductive organs.

13
The Scrotum
  • 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
  • During sexual arousal or cold conditions, scrotum
    retracts to keep testicle temperature consistent
    (about 93F) Cremaster muscle moves the scrotum
    closer to or farther from the body (protects)

14
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 tiny compressed tubes 1-3
    feet long
  • Production of sperm takes place in these tubes

15
Internal Structures Cross-Section of a Testis
16
Internal Structures
  • Epididymis Vas Deferens
  • The ducts that carry sperm from testicles to
    urethra for ejaculation
  • Sperm mature in epididymis, which joins with vas
    deferens
  • Vas deferens joins the ejaculatory duct within
    prostate gland
  • Vas deferens can be felt within scrotal sac

17
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
  • Cowpers (bulbourethral) glands
  • Secrete thick clear mucus prior to ejaculation

18
Male Sexual Physiology
  • Reproductive processes of the male body include
  • production of hormones
  • production and delivery of sperm

19
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
  • May affect personality

20
Testosterone Production
  • Testosterone is the most important male hormone
  • Interstitial, or Leydig, cells in the testicles
    produce testosterone out of cholesterol

21
Testosterone Fluctuations in a Day
22
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 motile
  • Upon ejaculation, sperm expelled through urethra
    by muscular contractions

23
Spermatogenesis
  • Seminiferous tubules produce and store sperm
  • Sertoli cells (in the tubules) provide nutrition
    for the development of sperm
  • This process begins with spermatogonium on the
    outer wall of the tubules they move toward the
    center during development as primary
    spermatocytes, then divide to form secondary
    spermatocytes, and divide again into spermatids

24
Spermatogenesis (Cont.)
  • Spermatids form the compact head covered by an
    acrosome that contains enzymes to penetrate the
    egg
  • The midpiece is formed and serves as the energy
    source
  • The flagellum propels the mature sperm
  • Sperm production takes 72 days, but is constant
    and each male produces about 300 million sperm a
    day

25
  • Figure 6.5 Spermatogenesis is continually taking
    place with various levels of sperm development
    throughout the testis.

26
Spermatogenesis
  • Immature sperm travel from the tubules to the
    epididymis organ that rests atop the testicle
  • Old and faulty sperm are reabsorbed here
  • They mature in 10-14 days in the epididymis
  • Upon maturity they are transferred to the vas
    deferens for storage

27
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 Cowpers glands appear at tip

28
The Ejaculatory Pathway
  • Ejaculation physiological process where seminal
    fluid is powerfully expelled from the penis
  • Pathway organs
  • Vas deferens
  • Seminal vesicles
  • Prostate gland
  • Cowpers glands

29
Ejaculation
  • Begins in the spinal cord once a threshold is
    reached, and proceeds until the conclusion

30
Ejaculation (Cont.)
  • Once the threshold is reached
  • Epididymis, seminal vesicles, and prostate empty
    their fluids into the urethral bulb
  • A sphincter closes off the bladder
  • 5-15 contractions at the base of the penis
    squeeze the urethral bulb
  • Ejaculate is expelled
  • Orgasm
  • Return to flaccid state

31
Ejaculation 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

32
Ejaculate/Semen
  • 2-5 milliliters of fluid
  • 50-150 million sperm per milliliter
  • Few sperm reach the ovum
  • Sperm work together in order to fertilize the egg
  • Semen coagulates upon ejaculation this helps it
    remain in the vagina and travel into the uterus
  • 5-20 minutes later it thins out

33
The Breasts and Anus
  • Male anatomical structures that do not serve a
    reproductive function but may be involved in
    sexual activities include
  • Breasts
  • Urethra
  • Buttocks
  • Rectum
  • Anus

34
The Male Maturation Cycle
  • Male puberty
  • Andropause

35
Male Puberty
  • Around 10 years of age, the hypothalamus starts
    to release gonadotropin releasing hormone (GnRH)
    which signals the pituitary to release FSH and LH
  • At the testes, LH stimulates testosterone
    production the two combine and FSH stimulate
    sperm production (around 12 years)
  • Negative feedback loop

36
  • Figure 6.6 The cycle of male hormones.

37
Male Puberty (Cont.)
  • Many organs and glands increase in size
    testicles, penis, epididymis, prostate, seminal
    vesicles, Cowpers glands
  • Growth spurt initiated by testosterone levels
  • Testosterone and DHT develop the secondary sex
    characteristics larger muscles and bones, pubic
    hair, thick and tough skin, deep voice, facial
    and chest hair, increased sex drive

38
Andropause
  • Testosterone levels decrease about 1 per year
    after 40 years of age
  • In the 70s and 80s, andropause occurs
  • Andropause symptoms decreased spermatogenesis,
    thinner ejaculate, less ejaculatory force, libido
    decreases, fatigue, mood disturbances, decreased
    strength
  • Controversy over hormone treatments

39
Male Reproductive and Sexual Health
  • Diseases of the male reproductive organs
  • Other conditions that affect the male
    reproductive organs
  • Cancer of the male reproductive organs

40
Diseases of the Male Reproductive Organs
  • Cryptorchidism testes do not descend into the
    scrotum surgery necessary to correct

41
Male Reproductive and Sexual Health
  • Diseases of the male reproductive organs
  • Other conditions that affect the male
    reproductive organs
  • Cancer of the male reproductive organs

42
Diseases of the Male Reproductive Organs
  • Cryptorchidism testes do not descend into the
    scrotum surgery necessary to correct

43
  • Figure 6.7 Although the testicles of a fetus
    begin high in the abdomen, they must descend into
    the scrotum during fetal development. If they do
    not, the male may become infertile.

44
Diseases of the Male Reproductive Organs
  • Testicular torsion testis is twisted on its
    spermatic cord many causes (sex, exercise,
    sleep) symptoms are pain and swelling immediate
    surgery is required to maintain the testicle

45
  • Figure 6.8 Testicular torsion can occur after
    exercise, sexual intercourse, and even while
    sleeping.

46
Diseases of the Male Reproductive Organs
  • Priapism persistent, painful erection not
    related to sexual excitement blood is trapped in
    erectile tissue common causes are drug use and
    unknown treatment is cessation of drug use and,
    possibly, surgery
  • Peyronies disease painful curvature of the
    penis making penetration impossible cause is
    unknown may disappear within 2 years, or require
    drugs or surgery

47
Other Conditions that Affect the Male
Reproductive Organs
  • Anabolic-androgenic steroid use synthetic
    testosterone can increase muscle mass and
    endurance there are also numerous physical,
    psychological, and emotional side effects,
    including erectile problems

48
Other Conditions that Affect the Male
Reproductive Organs (Cont.)
  • Inguinal hernia intestine goes through an
    abdominal opening into the scrotum, creating a
    bulge can be due to heavy lifting and straining
    surgery may be required
  • Hydrocele fluid accrues forms a scrotal mass

49
Cancer of the Male Reproductive Organs
  • Testicular
  • Penile
  • Prostate

50
Testicular Cancer
  • Most common cancer in men 15-44 years
  • Few early symptoms, early detection important
    testicular self-exam
  • Symptoms painless mass or hardness in the
    testes pain or increase in size of the testes,
    lower back pain, gynecomastia, shortness of
    breath, urethral obstruction
  • High cure rate radiation, chemotherapy, removal
    of testicle

51
Penile Cancer
  • Lesions on the penis may be benign or malignant
    and are usually treatable may also be a STI
  • Penile cancer is not common

52
Prostate Cancer
  • Prostate glands enlarge with age and this is
    typically unproblematic, other than interfering
    with urination
  • Prostate cancer is one of the most common in
    American men, typically in men over 50 years
  • Risk factors age, high fat diet, race, genetics
  • Symptoms pain in the lower back, pelvis, or
    upper thigh, and urinary abnormalities
  • Detected through rectal exam and blood test

53
Prostate Cancer (Cont.)
  • Treatments watchful waiting, radical
    prostatectomy, radiation, cryosurgery, drugs that
    attack cancerous cells
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