reproductive system

• Reproduction


  An essential characteristic of living organisms, and functional male and female reproductive systems are necessary for humans to reproduce
• Functions of the Reproductive System

  • Production of gametes
  • Fertilization
  • Development and nourishment of a new individual
  • Production of reproductive hormones
• Meiosis


  A type of cell division specialized for sexual reproduction
• Meiosis


  1. Meiosis I

  2. Meiosis II
• The reproductive organs in males and females produce gametes by meiosis
• Two consecutive cell divisions halve the chromosome number from 46 total chromosomes to 23 total chromosomes
• Meiosis ensures that the diploid number (46, in humans) is maintained in each generation
• Crossing over and random sorting of chromosomes during meiosis I produce genetic variation in gametes
• Anatomy of Male Reproductive System

  • Testes
  • Perineum
• Ducts System of Male Reproductive System

  • Epididymis
  • Ductus Deferens (Vas Deferens)
  • Urethra
• External Genitalia of Male Reproductive System

  • Penis
  • Scrotum
• Accessory Glands of Male Reproductive System

  • Seminal Vesicle
  • Prostate Gland
  • Bulbourethral Glands
• Spermatogenesis


  1. Spermatogonia divide (mitosis) to form primary spermatocytes

  2. Primary spermatocytes divide (first division of meiosis) to form secondary spermatocytes

  3. Secondary spermatocytes divide (second division of meiosis) to form spermatids

  4. Spermatids develop an acrosome and a flagellum to become sperm cells
• Sustentacular cells


  Nourish the sperm cells, form a blood-testis barrier and produce hormones
• Hormonal mechanisms that influence the male reproductive system

  Involve the hypothalamus, the pituitary gland, and the testes
• Regulation of Reproductive Hormone Secretion

  1. GRH is produced in the hypothalamus and released in surges

  2. GnRH stimulates LH and FSH release from the anterior pituitary

  3. LH stimulates the interstitial cells to produce testosterone

  4. FSH stimulates sperm cell formation

  5. Inhibin, produced by sustentacular cells, inhibits FSH secretion
• Puberty in Males


  • Before puberty, small amounts of testosterone inhibit GnRH release
  • Before birth, human chorionic gonadotropin (HCG) stimulates the synthesis and secretion of testosterone by the fetal testes
  • During puberty, testosterone does not completely suppress GnRH release, resulting in increased production of FSH, LH, and testosterone
• Testosterone


  • The major male hormone secreted by the testes
  • Classified as an androgen because it stimulates the development of male reproductive structures and male secondary sexual characteristics
• Effects of Testosterone


  • Causes the enlargement and differentiation of the male genitals and reproductive duct system and is necessary for sperm cell formation
  • Stimulates growth of thicker, coarser, pigmented hair
  • Affects the appearance of the skin, hypertrophy of the larynx and reduced tension on the vocal folds
  • Stimulates metabolism so that males have a slightly higher metabolic rate than females
• Male Sexual Behaviour and Act

  • Testosterone is required to initiate and maintain male sexual behavior
  • A complex series of reflexes that result in erection of the penis, secretion of mucus into the urethra, emission, and ejaculation
  • Sensations that are normally interpreted as pleasurable occur during the male sexual act and result in a climactic sensation, called orgasm, associated with ejaculation
  • After ejaculation, a phase called resolution occurs, characterized by a flaccid penis, an overall feeling of satisfaction and the inability to achieve erection and a second ejaculation for a period that can range from many minutes to many hours or longer
• Sensory Action Potentials and Integration

  1. Male sexual reflexes are initiated by a variety of sensory stimuli

  2. Action potentials are conducted by sensory neurons from the genitals through the pudendal nerve to the sacral region of the spinal cord, where reflexes that result in the male sexual act are integrated

  3. Action potentials travel from the spinal cord to the cerebrum to produce conscious sexual sensations

  4. Rhythmic massage of the penis, especially the glans penis, produces extremely important sensory action potentials that initiate erection and ejaculation

  5. Engorgement of the prostate and seminal vesicles with their secretions also causes sexual sensations

  6. Psychic stimuli, including sight, sound, odor, and thoughts, have a major effect on sexual reflexes
• Erection, Emission, and Ejaculation

  1. Erection is the first major component of the male sexual act

  2. First, action potentials travel from the spinal cord through the pudendal nerve to the arteries that supply blood to the erectile tissues

  3. Stimulation of the sexual act can be tactile or psychological

  4. Afferent action potentials pass through the pudendal nerve to the sacral region of the spinal cord

  5. Parasympathetic stimulation causes erection due to vasodilation of the blood vessels that supply the erectile tissue

  6. The glands of the urethra and the bulbourethral glands produce mucus

  7. Sympathetic stimulation causes erection, emission, and ejaculation
• Internal Genitalia of Female Reproductive System

  • Vaginal canal
  • Cervix
  • Fallopian tubes with fimbriae
  • Ovaries
  • Ligaments
• Ovaries


  • The female gonads, "homologous" to the testes in males
  • Consist of a cortex (outer part containing ovarian follicles) and a medulla (inner part with blood vessels, lymphatic vessels and nerves)
• Functions of the Ovaries

  Endocrine function - secretion of female hormones estrogen and progesterone
• Divisions of a Fallopian Tube

  • Interstitial
  • Isthmus
  • Ampulla
  • Infundibulum
• Functions of the Fallopian Tubes


  • Site of fertilization
  • Transport the ova from the ovaries to the uterus
• Parts of the Uterus

  • Fundus
  • Body (corpus)
  • Cervix
• Three Layers/Walls of the Uterus

  • Perimetrium
  • Myometrium
  • Endometrium
• Uterine Supporting Structures


  • Ligaments
  • Pelvic floor and supporting organs provide the main support
• Functions of the Uterus

  • Organ of menstruation
  • Site of implantation
  • Labor: it propels the products of conception into the vaginal canal
• Vagina


  • Distensible tube connecting the perineum to the cervix
  • Musculomembranous canal approximately 8 cm. long located between the rectum and the urethra
  • Ends in a blind pouch around the cervix
• Functions of the Vagina

  Serves as part of the birth canal and represents the female organ of copulation and passageway of menstruation
• Blood


  Shed during menstruation and following delivery
• THE FEMALE REPRODUCTIVE SYSTEM

  • Uterine Supporting Structures
  • Vagina
  • External Genitalia (Vulva / Pudendum)
  • Diseases
  • Physiology of Female Reproduction
  • Female Fertility and Pregnancy
  • Control of Pregnancy
  • Effects of Aging on the Reproductive System
• Uterine Supporting Structures


  • Ligaments - uterus is suspended in the pelvis by the broad ligament and anchored anteriorly and posteriorly by the round and uterosacral ligaments respectively
  • Pelvic floor and supporting organs provide the main support
• Functions of the Uterus

  • Organ of menstruation
  • Site of implantation
  • Labor - it propels the products of conception into the vaginal canal
• Vagina


  • Distensible tube connecting the perineum to the cervix
  • Musculomembranous canal approximately 8 cm. long located between the rectum and the urethra
  • Ends in a blind pouch around the cervix
• External Genitalia (Vulva / Pudendum)

  • Mons Pubis (Mons Veneris)
  • Labia Majora
  • Labia Minora
  • Clitoris
  • Vestibule
  • Hymen
  • Urethral Meatus
  • Fourchette
  • Perineum
• Mons Pubis (Mons Veneris)

  • Rounded fat pad anterior to the symphysis pubis covered with hair after puberty that is one to two years before the onset of menstruation
  • Serves to cushion the symphysis pubis