A+P 12 Organ Systems IV - Reproductive system

• Male reproductive system anatomy


  Ureter

  Urinary bladder

  Ductus (vascular) deferens

  Seminal vesicle

  Prostate gland

  Urethra

  Bulbourethral (cowper's glands)

  Prenis

  Epididymis

  Testes/testicles

  Scrotum
• Urethra


  Tube where semen and urine exit the body
• Penis


  Organ that inserts into the vagina during intercourse
• Testes/testicles


  Paired gonads that produce sperm and testosterone
• Scrotum


  Sac maintaining testes at cooler temp than abdominal cavity

  -necessary for viable sperm
• Epididymis


  Storage area for mature sperm
• Seminiferous tubules


  Produce sperm

  -coiled into lobes of testes
• Interstitial (leydig) cells


  Produce testosterone

  -surround seminiferous tubules
• Sustentacular (sertoli) cells


  Nourish developing sperm cells

  -found within seminiferous tubules
• Ductus (vas) deferens


  Transport mature sperm from testes to urethra
• Seminal vesicle


  Provide energy for sperm at time of ejaculation

  -secrete fructose
• Prostate gland


  Aids sperm survival

  -secretes milky basic fluid neutralizing vaginal acidity
• Bulbourethral (cowpers) glands


  Lubricates sperm

  -secretes mucus that protects sperm from acids in urethra
• Semen


  Thick whitish fluid ejaculated from urethra

  -contains ~400 million sperm + secretions from seminal vesicles, prostate gland, and cowpers glands
• The sperm cell


  Acrosome cap

  Head

  Mid piece

  Tail
• Acrosome cap


  Contains enzymes that penetrate outer barriers of the egg
• Head


  Contains nucleus
• Mid piece


  Contains mitochondria, provides energy for sperm movement
• Tail


  Contains flagella (movement) with 9+2 patters of micro tubules (cytoskeleton)
• Testosterone


  -promotes normal development & function of primary male sexual organs (penis/testes)

  -oversees development of sperm

  -causes development of secondary sexual characteristics during puberty - beard growth, axillary/pubic hair, deepened voice, greater muscle growth

  -increases secretions from oil/sweat glands, contributes to acne/body odor

  -fluctuating levels related to baldness, aggressiveness, sex drive
• Male hormone regulation - Gonadotropin releasing hormone (GnRH)


  Released by hypothalamus due to sexual stimulation
• Male hormone regulation - Follicle stimulating hormone (FSH) & Luteinizing hormone (LH)


  Produced by anterior pituitary, triggered by GnRH release

  - FSH promotes sperm production in seminiferous tubules, entering Sertoli cells +causes testosterone uptake

  - LH controls production of testosterone by interstitial cells
• Male hormone regulation - Inhibin


  Hormone released into blood by Sertoli cells as sperm is being produced (sperm production marker)
• Negative feedback loop


  - increased inhibin, increased testosterone level in blood detected by hypothalamus

  -increased testosterone caused decreased GnRH, LH release + inhibin causes decreased LH release, = sperm production shut down prior to ejaculation
• Male hormone regulation


  GnRH - released by hypothalamus during sexual arousal + tells ant. Pit to release LH (1) and FSH (2)

  (1) LH -> interstitial cells -> testosterone

  - testosterone increased, feeds back to hypothalamus and ant. Pit. And tells them to stop producing GnRH and LH

  (2) FSH -> seminiferous tubules -> sperm (plus inhibin)

  - increased inhibin feeds back to hypo + ant. Pit and tells them to stop producing GnRH and FSH
• Sperm travel


  Seminiferous tubules -> epididymes -> vas deferens -> urethra