Lecture Notes: Module 3 - Reproduction in Humans

Overview

• Module 3 of Unit 1 Biology focuses on human reproduction.
• Key Processes:
  • Gametogenesis:
    • Female: oogenesis
    • Male: spermatogenesis
  • Fertilization:
    • Egg fertilized by sperm
  • Ovarian and Uterine Cycles:
    • Key for understanding female reproductive cycle
  • Contraception:
    • Methods to prevent pregnancy
• Pregnancy Topics:
  • Development stages: fetus, placenta, mother
  • Contraceptive methods

Human Reproductive Systems

Male Reproductive System

• Testis:
  • Located in the scrotum
  • Sperm production happens in the epididymis
• Sperm Pathway:
  • Travels via the vas deferens
  • Fluids added by prostate gland, bulbourethral gland, and seminal vesicles to form semen
  • Semen exits body through urethra during ejaculation

Female Reproductive System

• Ovaries:
  • Egg production
• Fallopian Tubes (Oviducts):
  • Egg travels through here
  • Site of fertilization
• Uterus:
  • Endometrium: implantation site
  • Menstruation: shedding of endometrium if no fertilization occurs

Spermatogenesis

• Occurs in seminiferous tubules
• Involves mitosis and meiosis
• Hormonal Control:
  • Testosterone: Influences development of secondary sexual characteristics and facilitates spermatogenesis
  • Hypothalamus: Releases gonadotropin-releasing hormone (GnRH)
  • Anterior Pituitary Gland: Releases LH and FSH
    • LH: Stimulates Leydig cells to produce testosterone
    • FSH: Stimulates Sertoli cells, enhances sperm development

Process

• Begins with spermatogonia (mitosis)
• Develops into primary spermatocytes (meiosis)
• Results in haploid spermatids, which mature into sperm cells

Oogenesis

• Occurs in the ovaries
• Involves mitosis and meiosis
• Primary Oocyte: Arrested in prophase I until puberty
• Secondary Oocyte: Formed post-meiosis I; arrested in metaphase II until fertilization

Process

• Begun during fetal development
• Follicles: Primary, secondary, and graafian stages
• Hormonal Influence:
  • GnRH: Released from hypothalamus
  • FSH: Influences follicle development
  • Estrogen: Enlarge primary follicles, aids meiosis completion

Comparison of Spermatogenesis and Oogenesis

• Spermatogenesis yields four sperm per process
• Oogenesis yields one ovum and polar bodies

Hormonal Regulation

• Hypothalamic-Pituitary-Gonadal Axis:
  • GnRH: From hypothalamus
  • FSH & LH: From anterior pituitary
  • Estrogen & Progesterone: From ovaries
  • Negative feedback regulates hormone levels

Next Steps

• Further classes will cover:
  • Ovarian and uterine cycles
  • Contraception methods
  • Detailed pregnancy development stages

These notes summarize the lecture on human reproduction, focusing on the biological processes of gametogenesis, the anatomy of reproductive systems, and the hormonal regulation involved.