Male and Female Reproductive Systems

Male Reproductive System

• Male Reproductive Structures
  • External and internal genitalia.
  • Only system not essential for sustaining life.
  • Gonads produce gametes (sperm).

External Genitalia

• Penis
  • Contains erectile tissue; deposits sperm into the female vagina.
  • Urethra conducts semen to the exterior.
• Scrotum
  • Encases the testes.

Internal Genitalia

• Ductus deferens
  • Conducts sperm from the epididymis to the prostate.
• Seminal gland (seminal vesicle)
  • Secretes fluid contributing to semen volume.
• Prostate
  • Secretes fluids and enzymes into semen.
• Bulbourethral gland
  • Lubricates the penis tip with pre-ejaculatory fluid.
• Epididymis
  • Site of sperm maturation.
• Testis
  • Produces sperm and hormones (testosterone).

Sperm Transportation

• Sperm follows the path: testis ➔ epididymis ➔ ductus deferens ➔ ejaculatory duct ➔ urethra.

Accessory Organs

• Seminal glands, prostate, and bulbourethral glands secrete fluids into the reproductive tract to form semen.
• Urethra passes through the penis to exit the body.

Testes Development

• Form inside the body adjacent to the kidneys during fetal development.
• Connective tissue bands change position, positioning each testis into the scrotum.

Scrotum and Associated Structures

• Scrotal Cavity
  • Houses the testes, separated by the scrotal septum.
• Dartos Muscle
  • Smooth muscle that elevates testes.
• Cremaster Muscle
  • Pulls testes closer during arousal or cold temperatures.
• Spermatic Cords
  • Contain the ductus deferens, blood vessels, and nerves.
• Inguinal Canal
  • Can be prone to hernias; a weakness in the abdominal wall.

Internal Organization of the Testes

• Seminiferous tubules
  • Site of sperm production, connect to the rete testis and epididymis.
• Leydig cells
  • Produce androgens (e.g., testosterone).

Spermatogenesis

• Process involves:
  • Mitosis/cytokinesis, Meiosis, and Spermiogenesis.
• Mitosis:
  • Spermatogonia divide to form one primary spermatocyte and another remains as a stem cell.
• Meiosis:
  • Produces four haploid spermatids from each primary spermatocyte.
  • Takes 24 days; two meiotic divisions:
  • Meiosis I: Primary to secondary spermatocytes (haploid).
  • Meiosis II: Secondary to spermatids.
• Spermiogenesis:
  • Maturing of spermatids into sperm; occurs over 24 days.

Sperm Structure

• Head: Contains nucleus and acrosome (enzymes for fertilization).
• Neck: Contains centrioles.
• Middle piece: Contains mitochondria for ATP.
• Tail (flagellum): For movement.

Male Reproductive Tract

• Receives secretions from seminal, prostate, and bulbourethral glands.
• Activation of Sperm:
  • Capacitation process for increased motility and fertilization ability.
  • Sperm gains maturity within the epididymis before ejaculation.

Penis Structure and Function

• Conducts urine and semen to the exterior and delivers semen into the female’s vagina.

Regions

• Root: Fixed portion attaching to body wall.
• Body: Tubular, movable part.
• Glans penis (head): Surrounds external urethral orifice.

Erectile Tissue

• Corpora cavernosa: Two cylindrical masses.
• Corpus spongiosum: Surrounds the urethra; expands to form the glans.
• Erection Process:
  • Increased blood flow causes engorgement during sexual arousal.

Hormonal Regulation of Male Reproductive Function

• Hypothalamus: Secretes GnRH, stimulating LH and FSH production from the anterior pituitary.
• LH: Stimulates interstitial cells in testes to secrete testosterone.
• FSH: Stimulates nurse cells, promoting spermatogenesis.
• Inhibin: Provides feedback control to regulate spermatogenesis.

Female Reproductive System

• Overall Functions:
  • Produce sex hormones, functional gametes (oocytes), protect/support developing embryos, maintain fetus, and nourish infants.

Female Reproductive Structures

• External Genitalia (Vulva):
  • Clitoris, labia, mons pubis.
• Mammary Glands:
  • Produce milk post childbirth.

Internal Genitalia

• Ovaries: Produce immature oocytes and sex hormones.
• Uterine tubes: Carry oocytes; fertilization occurs here generally.
• Uterus: Supports the embryo/fetus and provides nourishment during development.
• Vagina: Receives sperm and serves as the birth canal.

Oogenesis

• Formation of oocytes, begins in fetal development and finished at ovulation post-puberty.
• Meiosis: Similar to spermatogenesis but results in one functional ovum and polar bodies from each primary oocyte.

Uterine Cycle

• Monthly cycle that prepares the endometrium for potential pregnancy.
• Phases:
  • Menstrual Phase: Sloughing of the endometrial layer.
  • Proliferative Phase: Repair and growth of the endometrium.
  • Secretory Phase: Secretion from uterine glands to support a possible embryo.

Hormonal Regulation of Female Reproductive Cycle

• Controlled by changes in hormone levels from hypothalamus and pituitary affecting ovarian and uterine cycles.

Conclusion

• Understanding male and female reproductive systems is crucial for comprehending reproduction, growth, and development processes, as well as associated health risks and hormonal interactions.