Reproductive System

• Reproductive system


  The function is to produce offspring, ranging from the production of gametes (eggs and sperm) to the birth of the baby and breastfeeding
• Components of the reproductive system

  • Primary sex organs (gonads)
  • Accessory reproductive organs (ducts, glands, external genitalia)
• Zygote

  the first cell of a new individual
• Male reproductive system

  • Produces male gametes (sperm) starting at puberty and delivers it to the female reproductive system through a system of ducts
• Components of the male reproductive system

  • Testes (gonads, primary sex organs)
  • Male duct system (epididymis, vas deferens, ejaculatory duct, urethra)
  • Male accessory glands (seminal vesicle, prostate)
  • External genitalia (penis, scrotum)

  
• Testes


  Male primary sex organs, glands that produce sperm and sex hormones (androgens, most importantly testosterone)

  
• Epididymis


  Tightly coiled tube on the superior part of the testis where sperm mature and are stored, expelled by contraction of smooth muscles in epididymis wall
• Vas deferens


  About 45 cm long, carries the sperm to the ejaculatory duct by peristalsis by a thick smooth muscle layer
• Urethra


  Extends from the base of the urinary bladder to the tip of the penis, carries both urine and sperm
• Accessory glands


  Produce secretions that together with the sperm compose the semen
• Scrotum


  • Sac of skin and fascia that maintains the testis at a temperature 3 degrees lower than the body temperature to favour spermatogenesis
  • changes position and surface area to maintain intrascrotal temperature
• Penis


  Copulatory organ designed to deliver sperm into the female reproductive tract, comprises two long cylindrical bodies of erectile tissue, a spongy network of connective tissue, smooth muscle and vascular spaces, that fill with blood during sexual excitement, each covered by connective tissue to contain the enlargement

  
• 2 Phases of male sexual response

  1. Erection

  2. Ejaculation
• Erection

  Enlargement and stiffening of the penis as a result of the engorgement of the erectile bodies with blood, under the control of the parasympathetic nervous system
• Ejaculation

  Discharge of semen from the male duct system, under the control of the sympathetic nervous system

  First the neurotransmitter released by the sympathetic nervous system (norepinephrine) causes the duct system and accessory glands to contract, pushing the semen to the beginning part of the urethra, where the smooth muscle will contract to expel the semen.
• Erectile dysfunction


  Recurrent inability to achieve and sustain an erection suitable for sexual intercourse, also called impotence
• Causes of erectile dysfunction

  • Vascular disease
  • Neurological disorders
  • Endocrine dysfunction
  • Psychological states
  • Trauma, chronic illness, medications, alcohol/recreational drugs, operations for prostate, bladder and colon cancer
• Treatments for erectile dysfunction

  • Education, communication, sex therapy
  • Medication (oral, penile injections, hormones)
  • Mechanical treatment (vacuum devices, penile implants)
• Inflatable penile implants


  Two inflatable cylinders positioned inside the penis, connected through tubing to a pump and a valve placed in the scrotum, and a reservoir with saline fluid placed under the lower abdominal muscles
• Flexible/malleable penile implants


  Two flexible rods positioned inside the penis, an 'erection' is created by bending the rods in a straight position -> permanent firmness of penis
• Low-intensity extracorporeal shockwave therapy (Li-ESWT)


  Non-invasive treatment that involves the application of acoustic waves to the penile tissue to enhance blood flow and stimulate the natural repair mechanisms of the body
• Biological mechanisms of Li-ESWT

  • Neoangiogenesis
  • Nitric oxide production
  • Anti-inflammatory activity
  • Nerve regeneration
  • Fibrosis reduction
• Components of the female reproductive system


  • Ovaries (gonads, primary sex organs)
  • Female duct system (uterine tubes, uterus, vagina)
  • External genitalia
  • Mammary glands

  
• Ovaries


  Female primary sex organs, glands that produce eggs and sex hormones (progesterone and estrogen)
• Uterine tubes


  Each 10 cm long, receive the ovulated oocyte and are the site where fertilization occurs, transport the oocyte towards the uterus
• Uterus


  5 cm wide, 8-10 cm long, hollow, thick-walled, muscular organ that receives, retains and nourishes the fertilized egg
• Vagina


  1. 10 cm long tube between the bladder and the external genitalia
• Ovulation


  Event where an oocyte is released from the ovary
• Uterine tubes


  • Each 10 cm long
  • Receive the ovulated oocyte
  • Site where fertilization occurs
  • Transport oocyte towards uterus by muscular peristalsis and cilia beating
  • Not continuous with ovaries
• Ectopic pregnancy


  Can occur due to uterine tubes not being continuous with ovaries
• Infection of peritoneal cavity by sexually transmitted microorganisms


  Can cause scarring of uterine tubes and ovaries leading to infertility
• Uterus


  • 5 cm wide, 8-10 cm long
  • Hollow, thick-walled, muscular organ
  • Receives, retains and nourishes the fertilized egg
  • Narrow neck called cervix
  • Mucosal lining (endometrium) grows monthly and is shed or provides environment for implantation
• Vagina


  • 8-10 cm long tube
  • Female organ of copulation and birth canal
• External genitalia


  • Female reproductive structures that lie external to the vagina
• Mammary glands


  • Produce milk to nourish the newborn baby
• Events from fertilization to birth

  1. Fertilization (Zygote)

  2. Embryonic development (until week 8)

  3. Fetal development (from week 9)

  4. Labour (childbirth)
• Sperm


  • Head: 3x5 μm, contains nucleus with 23 chromosomes and acrosome with enzymes
  • Tail (flagellum): 50 μm, facilitates movement
  • Midpiece: 75-100 mitochondria for energy production

  
• Egg


  • Diameter ~ 120 μm
  • Cytoplasm: 100,000-200,000 mitochondria
  • Cortical granules
  • Nucleus with 23 chromosomes
  • Corona radiata and zona pellucida

  
• The oocyte is viable for 12 to 24 hours after ovulation. One oocyte.
• Sperm are viable for up to 5 days after ejaculation. Ca. 300 million sperm.