Module 3: Sexual Reproduction in Humans

Overview

• Module 3 in Unit 1 Biology focuses on reproduction, specifically sexual reproduction in humans.
• Humans are classified as male or female.
• Reproduction involves creation of gametes:
  • Females: Oogenesis.
  • Males: Spermatogenesis.

Process of Reproduction

1. Gametogenesis:
   • Formation of gametes (eggs in females, sperm in males).
2. Fertilization:
   • Sperm fertilizes egg.
3. Cycles:
   • Ovarian and Uterine cycles in females.
4. Contraception:
   • Methods to prevent pregnancy.

Male Reproductive System

• Components:

  • Testis: Sperm production.
  • Scrotum: Contains testis.
  • Epididymis: Sperm maturation.
  • Vas deferens: Sperm transportation.
  • Prostate gland: Adds fluid to sperm.
  • Bulbourethral gland: Adds fluid to sperm.
  • Seminal vesicles: Adds fluid to sperm.
  • Urethra and Penis: Semen ejaculation.

• Spermatogenesis:

  • Occurs in seminiferous tubules.
  • Testosterone regulates from puberty onset.
  • Involves mitosis and meiosis.
  • Hormonal Control:
    • Hypothalamus releases GnRH.
    • Anterior pituitary releases LH and FSH.
    • Leydig cells produce testosterone.
    • Sertoli cells assist in sperm development.

Female Reproductive System

• Components:

  • Ovary: Egg production.
  • Fallopian tubes (Oviducts): Egg passage.
  • Uterus: Fertilized egg implantation.
  • Cervix and Vagina: Pathway for childbirth.

• Oogenesis:

  • Ugonia: Germinal cells in ovaries.
  • Primary Oocyte: Begins meiosis I (arrested at prophase I).
  • Secondary Oocyte: Completes meiosis I, enters meiosis II.
  • Follicle Development:
    • Primordial Follicle: Contains primary oocyte.
    • Primary Follicle: More cell layers, granulosa cells produce hormones.
    • Secondary Follicle: Contains haploid secondary oocyte.
    • Graafian Follicle: Mature follicle.
  • Meiosis II: Completed upon fertilization.

• Hormonal Control:

  • GnRH from hypothalamus, FSH from anterior pituitary.
  • Estrogen and progesterone produced by ovaries.

Hormonal Feedback Loops

• Negative Feedback:
  • High testosterone inhibits pituitary and hypothalamus hormone release.
  • High estrogen/progesterone levels provide negative feedback in females.

Comparison of Gametes

• Sperm: Small, motile, produced in large numbers.
• Egg: Larger, non-motile, produced in smaller numbers.

Upcoming Topics

• Ovarian and Uterine Cycles: Detailed explanation in future lectures.
• Contraception and Pregnancy: To be discussed further.