Review of Chapter 81: Male Reproductive System (Guyton and Hall’s Medical Physiology)

Functions of the Male Reproductive System

1. Spermatogenesis: Formation of sperm.
2. Sexual act: Involves physiological processes leading to ejaculation.
3. Hormonal regulation: Various hormones regulate these processes.

Anatomy of the Male Reproductive System

• Testes: Sperm produced in seminiferous tubules.
• Epididymis: Where sperm mature and are temporarily stored.
• Vas deferens: Pathway for sperm to reach the prostate gland.
• Ejaculatory duct: Final pathway before entering the urethra.

Spermatogenesis

• Spermatogonia: Original germ cells dividing via mitosis at puberty.
• Sertoli Cells: Provide nutrition to developing sperm cells.
• Primary Spermatocytes: Undergo meiosis to form spermatids.
• Spermatids: Mature into sperm with head and tail morphology.
• Sex Chromosomes: X and Y chromosomes determine sex of offspring.

Anatomy and Function of Sperm

• Acrosome: Contains enzymes to penetrate egg.
• Flagellum: Propels sperm forward.
• Sperm motility is developed in the epididymis and after ejaculation.

Hormonal Regulation

• Testosterone: Secreted by Leydig cells, stimulates sperm development.
• Luteinizing Hormone (LH): Stimulates testosterone production.
• Follicle Stimulating Hormone (FSH): Stimulates Sertoli cells for sperm maturation.
• Growth Hormone: Supports metabolic functions.

Movement and Storage of Sperm

• Non-motile in seminiferous tubules; gain motility in the epididymis.
• Stored in epididymis for up to a month.

Role of Fluids

• Seminal Vesicles: Produce nutrient-rich fluid.
• Prostate Gland: Produces alkaline fluid aiding sperm survival.
• Semen Composition: Mix of sperm and glandular fluids.

Capacitation

• Process in female reproductive tract enabling sperm to fertilize ovum.
• Involves removal of inhibitory factors and cholesterol.

Male Sexual Act

• Sensory Nerve Signals: Initiate from glans penis; can also be psychologically induced.
• Erection: Parasympathetic response causing blood vessel dilation.
• Ejaculation: Sympathetic response leading to expulsion of semen.

Hormones and Androgens

• Testosterone: Primary androgen affecting masculine characteristics.
• Fetal Development: Testosterone leads to male organ development.
• Puberty: Increase in testosterone causes physical male characteristics.

Hormonal Control

• Hypothalamus: Releases GnRH.
• Anterior Pituitary Gland: Releases LH and FSH.
• Negative Feedback: Regulates hormone levels.

Additional Notes

• hCG in pregnancy: Stimulates fetal testosterone production.
• Childhood: Low hypothalamic activity prevents testosterone production.