Reproductive

• Egg (or oocyte)


  Contains the X chromosome (only!)

  
• Sperm cell (or spermatozoan)


  Contains either the X or Y chromosome

  
• Genetic female


  Oocyte containing an X chromosome combines with a spermatozoan containing an X chromosome

  
• Genetic male


  Oocyte containing an X chromosome combines with a spermatozoan containing a Y chromosome

  
• Sexual differentiation


  1. When an embryo/fetus that is XY develops testes, male sex hormones are produced from the testes which aid in providing male sexual characteristics

  2. If ovaries develop, the lack of male sex hormone results in the expression of female sexual characteristics

  
• Secondary sexual characteristics that develop at the onset of puberty


  • Examples not provided
• Primary male reproductive organ


  Testes - functions in production of spermatozoa (sperm) and androgens (testosterone)

  
• Primary female reproductive organ

  Ovaries - functions in production of ova (egg) and estrogen/progesterone

  
• Secondary reproductive organs in both males and females

  • Ducts, glands, and organs with functions of sperm/egg transport, hormone production, and copulation
• Scrotum


  • Sac of skin and superficial connective tissue that protects and supports the testes
  • Contains smooth muscle (dartos) and skeletal muscle (cremaster) that act to raise and lower the testes to maintain optimal temperature (95°F) for spermatogenesis
• Descent of testes


  1. Gubernaculum helps guide the testes down the inguinal canal and into the scrotum

  2. Undescended testes (cryptorchidism) fail to produce sperm later in life due to high abdominal temperature
• Structure of testes


  • Composed of lobules separated by connective tissue tunics (vaginalis, albuginea)
  • Seminiferous tubules are the actual "sperm-producing factories"

  
• Spermatogenesis


  1. Sertoli cells form the blood-testis barrier to protect developing sperm

  2. Spermatogonia undergo meiosis to produce haploid spermatozoa

  3. Sperm cells mature as they move from the outer rim to the lumen of the seminiferous tubules

  4. Entire process takes 64 days and produces ~400 million sperm per day

  
• Parts of a spermatozoan

  Head contains DNA, midpiece contains mitochondria for ATP, tail is the flagellum for motility, acrosome contains digestive enzymes

  
• Interstitial cells (Leydig cells)


  Produce the male sex hormone testosterone
• Maturation of sperm in epididymis


  Sperm spend several weeks in epididymis further maturing and becoming functionally capable of fertilization

  
• Vas deferens


  Muscular tube that forms part of the spermatic cord and transports sperm from the epididymis to the ejaculatory duct
• Urethra


  Has three sections - prostatic, membranous, and penile
• Glands that contribute to seminal fluid

  • Seminal vesicles, prostate gland, bulbourethral (Cowper's) glands
• Seminal vesicle secretions


  Fructose (for sperm fuel), clotting factors (for sperm clumping), prostaglandins (for smooth muscle stimulation)
• Prostate cancer is the most common cancer and the second leading cause of cancer deaths in males
• Bulbourethral gland secretions


  Serve as a lubricant and neutralize the urinary tract pH prior to ejaculation
• Pathway of sperm


  • Seminiferous tubules
  • Rete testis
  • Vas efferens
  • Epididymis
  • Vas deferens in spermatic cord
  • Ejaculatory duct
  • Prostatic urethra
  • Membranous urethra
  • Penile urethra

  
• Penis


  Functions to expel urine and semen, composed of erectile tissue (corpus cavernosum and corpus spongiosum) with extensive blood supply for erection
• Erection, orgasm, and ejaculation

  During erection, blood vessels in erectile tissue become filled with blood as arteries dilate
• Spermatic cord


  Through inguinal canal

  
• Ejaculatory duct


  Near seminal vesicles
• Prostatic urethra


  Near prostate gland
• Membranous urethra


  Near bulbourethral glands
• Penis


  • Functions to expel both urine and semen out of the body
• Erectile tissue


  Arranged in columns, three of them
• Corpus cavernosum


  Two erectile columns
• Corpus spongiosum


  One erectile column, easily identified because the urethra passes through
• Penis contains many sensory receptors
• Penis


  • Contains many blood vessels; very vascular; extensive blood supply allows for penis to become rigid for sexual intercourse
• Erection


  Blood vessels within erectile tissue become filled with blood as arteries dilate and venous outflow is reduced
• Orgasm


  Culmination of sexual stimulation, accompanied by a rise in BP, HR, breathing
• Ejaculation


  Movement of semen accomplished by sympathetic impulses to smooth-muscle lined semen conducting tubules
• Following ejaculation, penis becomes flaccid
• Neurotransmitter for erection


  Nitric Oxide (NO)