week 5

• Testes


  • Testes are 2 male reproductive gonads
  • Produce androgens (male sex hormones) and sperm (spermatogenesis)
  • Spermatic cord: suspends each testis in the scrotum, and contains the vas deferens, blood vessels, and nerves
  • Cremaster muscle surrounds testes and pulls up/lowers them (in response to temperature and other stimulation) in part for sperm health
• Seminiferous tubules


  • Packed inside the testes
  • Produce and store sperm (spermatogenesis)
• Seminal vesicles


  • 2 tubular glands next to the prostate gland near the ends of the vas deferens
  • Contribute a sugary, alkaline fluid that makes up approximately 70% of the ejaculate fluid
  • Main proteins from seminal vesicles create gel that immobilizes sperm
• Prostate gland


  • Lies directly below the bladder
  • Secretes a thin, milky, alkaline fluid, resulting in a chemically safe environment to maintain sperm
  • The alkalinity of semen counteracts the harmful acidity of the penile urethra and the vagina
  • PSA (a protein) from prostate liquifies gel produced by seminal vesicles, allowing sperm to become independently mobile and swim after ejaculation
• Cowper's glands


  • Two pea-sized structures that lie on each side of the urethra below the prostate
  • Their ducts empty into the urethra
  • They secrete pre-ejaculate (pre-cum) that prepares the urethra for the ejaculate upon sexual arousal
  • This pre-ejaculatory fluid may contain active and healthy sperm

  
• Seminal fluids

  • The alkalinity of the fluid serves to neutralize the normally acidic environment in the distal urethra and in the vagina
  • The fructose is supplied as an energy source for the sperm, and the prostaglandins serve to stimulate smooth muscle contractions in the vagina and cervix, facilitating the uptake of sperm into the uterus
• Semen production

  • Semen provides a transport medium for the sperm, as well as nutrients and chemicals that protect, activate, and facilitate their movement
  • The amount of semen released during ejaculation is relatively small, about 1 teaspoon, but it contains 200-500 million sperm
  • Semen amount affected by: 1) time since last ejaculation; 2) length of time of arousal before ejaculation; and 3) age
  • Semen is primarily made up of fluid from the seminal vesicles and the prostate gland
• Ejaculation

  1. A spinal reflex is initiated, producing a sympathetic discharge to the genital organs

  2. The reproductive ducts and accessory glands contract peristaltically, discharging their contents into the urethra

  3. The muscles of the penis undergo a rapid series of contractions propelling semen from the urethra

  4. This is followed by muscular and psychological relaxation and vasoconstriction of the arterioles serving the penis, allowing blood to drain out of the erectile tissue, which subsequently causes the penis to become flaccid again
• Resolution phase


  • The sexual system returns to its unaroused state
  • Physiological changes in males and females
• Near 100% of males orgasm through intercourse, while most females do not orgasm "solely" through intercourse alone
• Health benefits of orgasms

  • Strengthen immune system
  • Pain relief (relief from menstrual cramps & increase pain tolerance)
  • Lower cancer rate (reduces prostate cancer risk later in life)
  • Mood enhancement (improves mood and reduces depression in women)
  • Longer life
  • Less heart disease
  • Better sleep