M23

• Reproductive system


  The system responsible for the production of gametes, fertilization, and development of a new individual
• Functions of reproductive system


  • Production of gametes
  • Fertilization of the oocyte by the sperm
  • Development and nourishment of a new individual
  • Production of reproductive hormones
• Meiosis

  1. Meiosis I (Reduction Division)

  2. Meiosis II

  3. Prophase

  4. Metaphase

  5. Anaphase

  6. Telophase

  7. Starts with 46 chromosomes

  8. Crossing over in middle prophase I

  9. Produces 4 daughter cells with 23 chromosomes each
• Male reproductive system


  Consists of testes, series of ducts, accessory glands, and supporting structures

  
• Scrotum


  • Saclike structure containing the testes
  • Muscles that regulate temperature in testes for normal sperm development
• Testes / Male gonads


  • Oval organs within scrotum
  • Divided into about 250 cone-shaped lobules
  • Develop in abdominopelvic cavity and descend at 7th or 8th month of fetal development or shortly after birth
  • Seminiferous tubules - site of sperm cell development
  • Interstitial cells / Leydig cells - secrete testosterone
  • Germ cells - where sperm cells begin
  • Sustentacular cells / Sertoli cells - nourish the germ cells and produce hormones

  
• Spermatogenesis


  1. Germ cells

  2. Spermatogonia (undeveloped sperm cells) - divide by mitosis

  3. Primary spermatocytes - divide by meiosis

  4. Secondary spermatocytes

  5. Spermatids - two smaller cells

  6. Sperm cells / Spermatozoon - consist of head, midpiece, and tail

  7. Acrosome - vesicle with enzymes for fertilization

  8. Capacitation - final changes in sperm cells after ejaculation
• Sperm travel route


  • Seminiferous tubules of testes
  • Epididymis (maturation)
  • Ductus deferens
  • Accessory glands
  • Urethra

  
• Rete testis


  • Tubular network where seminiferous tubules converge
• Efferent ductules

  • 15-20 tubules where rete testis empties, carry sperm cells from testis to epididymis
• Epididymis


  • Tightly coiled series of tubules on posterior side of testis where sperm cells continue to mature

  
• Ductus deferens / Vas deferens


  • Emerges from epididymis, associated with blood vessels and nerves, contains smooth muscle for peristaltic waves
  • Ampulla of the ductus deferens - area of increased diameter before prostate gland
• Spermatic cord


  • Surrounded by cremasteric muscle and connective tissue sheaths, contains ductus deferens, testicular artery and veins, lymphatic vessels, and testicular nerve

  
• Urethra


  • Passageway for both urine and male reproductive fluids
  • Prostatic urethra, membranous urethra, spongy urethra

  
• Penis


  • Male organ of copulation, consists of three columns of erectile tissue
  • Glans penis - cap at distal end
  • External urethral orifice - opening of spongy urethra
  • Prepuce / Foreskin - loose fold of skin covering glans penis

  
• Semen


  • Mixture of sperm cells and secretions from male reproductive glands
  • Seminal vesicle - produces thick, mucus-like secretion
  • Prostate gland - secretes thin, milky prostatic fluid
  • Bulbourethral glands - secrete mucus for lubrication and pH regulation
• Physiology of male reproduction

  • Depends on hormonal mechanisms and neural mechanisms
• Regulation of reproductive hormone secretion

  • Luteinizing hormone (LH) - binds to interstitial cells to secrete testosterone
  • Follicle-stimulating hormone (FSH) - binds to sustentacular cells to promote sperm development and increase inhibin secretion
• Puberty


  • Sequence of events transforming a child into a young adult
  • Begins at 12-14 years old, largely completed by 18
  • Elevated FSH and LH levels promote spermatogenesis and testosterone secretion
• Effects of testosterone


  • Relatively constant blood levels from puberty to 40 years old
  • Slow decrease in sex drive and fertility by age 80 due to 20% decline
  • Causes male sexual behavior and male sex act (erection, emission, ejaculation, orgasm, resolution, nocturnal emission)
• Cryptorchidism - failure of testes to descend into scrotum, can lead to sterility
• Inguinal hernia - enlarged or ruptured inguinal canal allowing intestine to protrude
• Male pattern baldness - genetic, develops in response to testosterone and other androgens
• Infertility - low sperm count, abnormal sperm structure, reduced sperm motility
• Artificial insemination - alternative process to achieve fertility by collecting and concentrating sperm for insertion into female reproductive tract
• Benign prostatic enlargement and prostate cancer are common in elderly men
• Female reproductive system


  Consists of ovaries, uterine tubes, uterus, vagina, external genitalia, and mammary glands

  
• Oogenesis and fertilization

  1. Ovulation - release of oocyte from ovary

  2. Fertilization - sperm penetrates oocyte cytoplasm

  3. Zygote forms

  4. Uterine tubes receive oocyte

  5. Fimbriae sweep oocyte into tubes

  6. Ampulla - site of fertilization

  7. Implantation - fertilized oocyte embeds in uterine wall
• Uterus


  • Pear-shaped organ with fundus, body, and cervix
  • Uterine cavity located within
• Female reproductive organs

  • Ovaries
  • Uterine tubes / Fallopian tubes
  • Uterus
  • Vagina
  • External genitalia
  • Mammary glands
• Oogenesis and Fertilization

  1. Ovulation - release of an oocyte from an ovary

  2. Fertilization - sperm cell penetrates cytoplasm of secondary oocyte

  3. Zygote formation - when fertilization is completed
• Uterine Tubes / Fallopian Tubes / Oviduct


  • Open directly into the peritoneal cavity near each ovary and receive the secondary oocyte
  • Fimbriae - long, thin processes surrounding the opening of each uterine tube & nearly surround the surface of ovary; contain cilia that sweep the oocyte into the uterine tubes
  • Ampulla - part of the tube near the ovary where the fertilization usually occurs
• Implantation


  • Fertilized oocyte travels to the uterus and embeds in the uterine wall
• Uterus


  • Pear-sized organ with fundus, body, and cervix
  • Uterine Cavity - located in fundus and body that continues to the cervix
  • Cervical Canal - continues internally which opens into the vagina; lined with mucous glands
• Uterine Wall


  • Composed of perimetrium/serous layer, myometrium/muscular layer, and endometrium

  
• Vagina


  • Female organ of copulation that receives the penis during intercourse; allows menstrual flow & childbirth
  • Hymen - a thin mucous membrane that covers the vagina during young age; can be perforated or torn in variety of activities making it unreliable indicator of virginity
• External Genitalia / Vulva / Pudendum


  • Vestibule
  • Greater Vestibular Glands
  • Labia Minora
  • Clitoris
  • Prepuce
  • Labia Majora
  • Mons Pubis
  • Pudendal Cleft
  • Clinical Perineum
• Episiotomy


  • An incision made during childbirth to prevent the tearing of skin and muscle in perineum
• Mammary Glands


  • Organs of milk production and located in the breasts
  • Lactiferous Duct - opens independently to the surface of nipple which forms a secretory sac, the alveoli, in a lactating mammary gland
  • Myoepithelial Cells - contract to expel milk from alveoli
  • Nipple - raised area in each breast surrounded by circular, pigmented area called areola; very sensitive to tactile stimulation which contracts and becomes erected
• Puberty


  • Initial change results most likely in maturation of hypothalamus
  • Typically begins between ages 11 & 13, completed by age 16
  • Menarche - first episode of menstrual bleeding
  • Sexual characteristic changes occur due to increasing rate of estrogen & progesterone secretion by the ovaries
  • After onset, the hypothalamus & anterior pituitary secrete large amounts of GnRH, LH, & FSH