Lecture Notes: Reproductive Systems - The Male Aspect

Key Themes

• Differences between male and female reproductive strategies
• Anatomy and function of male reproductive organs
• Process and significance of spermatogenesis
• Hormonal regulation in male reproduction

Introduction

• Sex as a Gamble: Mental and emotional risks in relationships.
  • Female Gamete: Large biological investment.
  • Male Gamete: Small, numerous, less investment.

Female vs. Male Reproductive Strategies

• Female: High-stakes, single egg developed over a year.
• Male: Penny slots strategy with many small sperm.

Male Reproductive System

• Testes: Produce sperm and testosterone.
  • Located outside the body due to temperature sensitivity.
  • Divided into lobules with seminiferous tubules.
  • Sertoli Cells: Nourish sperm.
  • Leydig Cells: Secrete testosterone.

Spermatogenesis

• Comparison to skin cell production; cheap and easy.
• Hormonal Cascade: At puberty, GnRH prompts LH and FSH release.
  • LH: Stimulates testosterone release from Leydig cells.
  • FSH: Triggers Sertoli cells to release ABP.
• Spermatogonia: Stem cells divide to form primary spermatocytes.
  • Primary spermatocytes undergo meiosis to form spermatids.
  • Spermiogenesis: Spermatids become mobile sperm.
  • Process duration: ~5 weeks.

Path of Sperm

• From Testes: Through epididymis for maturation.
• Epididymis: Stereocilia absorb fluid, nutrients provided.
  • Sperm gain mitochondria and motility.
• Ejaculation Path: Epididymis ➔ vas deferens ➔ ejaculatory duct ➔ urethra.

Semen and Gland Contributions

• Seminal Vesicles: Alkaline fluid with enzymes and fructose.
• Prostate Gland: Citric acid and enzymes.
• Bulbo-urethral Glands: Clear mucus to clear acidic urine.

Anatomy of the Penis

• Structure: Shaft, glans, foreskin.
• Function: Delivery system for sperm.

Conclusion

• Next Topic: Fertilization
• Acknowledgments: Contributors to Crash Course video series.

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