Tutorial Physiology March 5

Overview of Male Reproductive System and Spermatogenesis

• The male reproductive system is designed to produce gametes (sperm) and contribute to fertilization.

• Its primary goal is to maintain homeostasis while creating new life through reproduction.

Hormones Involved

• Luteinizing Hormone (LH):

  • Regulates testosterone production from Leydig cells.

• Follicle Stimulating Hormone (FSH):

  • Stimulates Sertoli cells to promote spermatogenesis.

Components of the Male Reproductive System

• Bladder:

  • Stores urine.

• Prostate:

  • Secretes fluid that nourishes and protects sperm, aiding its transport.

• Penis:

  • Conduit for urine and semen.

• Urethra:

  • Tube that allows urine and semen to exit the body.

• Testes:

  • Produce sperm and testosterone, critical for male reproductive function.

• Vas Deferens:

  • Connects epididymis to urethra, transporting sperm.

• Ejaculatory Duct:

  • Connects vas deferens and urethra, facilitating the expulsion of semen.

• Epididymis:

  • Site of sperm maturation and storage.

Pathway of Sperm Production

1. Seminiferous Tubules:

   • Site of sperm production within the testes.

2. Epididymis:

   • Where sperm mature and are stored.

3. Vas Deferens:

   • Carries sperm to ejaculatory duct.

4. Ejaculatory Duct:

   • Joins sperm with seminal fluid before entering the urethra.

5. Urethra:

   • Sperm exits body.

Spermatogenesis Process

• Spermatogonia (stem cells) duplicate to form primary spermatocytes (diploid).

• Meiosis I:

  • Primary spermatocytes divide into secondary spermatocytes (haploid).

• Meiosis II:

  • Secondary spermatocytes divide to form spermatids.

• Spermatids:

  • Undergo maturation to become sperm cells, achieving their final shape and function.

Structure of Sperm Cells

• Head:

  • Contains genetic material; pointed to penetrate the egg.

• Midpiece:

  • Contains mitochondria for energy, necessary for the swimming motion of sperm.

• Tail:

  • Propels the sperm forward to reach the egg.

• Acrosome:

  • Enzyme-filled structure that helps sperm penetrate the egg.

Unique Aspect of Sperm Production

• Approximately 40-80 million sperm are produced per ejaculation, but only one typically fertilizes an egg.

Role of Hormones in Spermatogenesis

• Testosterone:

  • Crucial for sperm production and male characteristics, produced by Leydig cells, stimulated by LH.

• Negative Feedback:

  • Elevated testosterone levels feedback to hypothalamus to inhibit GnRH, LH, and FSH production, regulating sperm production.

General Notes on Reproductive Hormones and Spermatogenesis

• Spermatogenesis takes about 64-72 days to complete.

• Understanding the interplay of FSH, LH, and testosterone is essential for grasping male reproductive function and homeostasis.