Sex organs serve a reproductive function



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Sex organs serve a reproductive function

  • 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


Penis, Scrotum

  • Penis, Scrotum



Penis: from Latin word for tail

  • 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



Myths about the penis abound

  • 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.


Three main sections:

  • 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


Extends into the body below the pubic bone

  • Extends into the body below the pubic bone

  • Attached to internal pelvic muscles and can be felt in the perineum



  • Figure 6.1 The internal structure of the penis.





Glans penis: head of penis; most sensitive

  • 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.


Foreskin: sleeve-like covering of the glans

  • 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


  • Figure 6.2 The male reproductive organs.



Scrotum: a pouch of skin that holds the two testicles

  • 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 93°F) Cremaster muscle moves the scrotum closer to or farther from the body (protects)


Testes:

  • 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




Epididymis & Vas Deferens

  • 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


Seminal vesicles

  • 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


Reproductive processes of the male body include:

  • Reproductive processes of the male body include:

    • production of hormones
    • production and delivery of sperm


Testosterone

  • 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


Testosterone is the most important male hormone

  • Testosterone is the most important male hormone

  • Interstitial, or Leydig, cells in the testicles produce testosterone out of cholesterol





Ongoing process from puberty onward

  • 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


Seminiferous tubules produce and store sperm

  • 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



Spermatids form the compact head covered by an acrosome that contains enzymes to penetrate the egg

  • 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



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

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



Immature sperm travel from the tubules to the epididymis; organ that rests atop the testicle

  • 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



Erection

  • 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 – physiological process where seminal fluid is powerfully expelled from the penis

  • Ejaculation – physiological process where seminal fluid is powerfully expelled from the penis

  • Pathway organs:

    • Vas deferens
    • Seminal vesicles
    • Prostate gland
    • Cowper’s glands


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

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



Once the threshold is reached:

  • 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


Emission stage

  • 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


2-5 milliliters of fluid

  • 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



Male anatomical structures that do not serve a reproductive function but may be involved in sexual activities include:

  • Male anatomical structures that do not serve a reproductive function but may be involved in sexual activities include:

    • Breasts
    • Urethra
    • Buttocks
    • Rectum
    • Anus


Male puberty

  • Male puberty

  • Andropause



Around 10 years of age, the hypothalamus starts to release gonadotropin releasing hormone (GnRH) which signals the pituitary to release FSH and LH

  • 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



  • Figure 6.6 The cycle of male hormones.



Many organs and glands increase in size: testicles, penis, epididymis, prostate, seminal vesicles, Cowper’s glands

  • Many organs and glands increase in size: testicles, penis, epididymis, prostate, seminal vesicles, Cowper’s 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



Testosterone levels decrease about 1% per year after 40 years of age

  • 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



Diseases of the male reproductive organs

  • Diseases of the male reproductive organs

  • Other conditions that affect the male reproductive organs

  • Cancer of the male reproductive organs



Cryptorchidism – testes do not descend into the scrotum; surgery necessary to correct

  • Cryptorchidism – testes do not descend into the scrotum; surgery necessary to correct



Diseases of the male reproductive organs

  • Diseases of the male reproductive organs

  • Other conditions that affect the male reproductive organs

  • Cancer of the male reproductive organs



Cryptorchidism – testes do not descend into the scrotum; surgery necessary to correct

  • Cryptorchidism – testes do not descend into the scrotum; surgery necessary to correct



  • 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.



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

  • 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



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



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

  • 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

  • Peyronie’s disease – painful curvature of the penis making penetration impossible; cause is unknown; may disappear within 2 years, or require drugs or surgery



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

  • 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



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

  • 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



Testicular

  • Testicular

  • Penile

  • Prostate



Most common cancer in men 15-44 years

  • 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



Lesions on the penis may be benign or malignant and are usually treatable; may also be a STI

  • Lesions on the penis may be benign or malignant and are usually treatable; may also be a STI

  • Penile cancer is not common



Prostate glands enlarge with age and this is typically unproblematic, other than interfering with urination

  • 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



Treatments: “watchful waiting”, radical prostatectomy, radiation, cryosurgery, drugs that attack cancerous cells

  • Treatments: “watchful waiting”, radical prostatectomy, radiation, cryosurgery, drugs that attack cancerous cells







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