Male Reproductive System Lecture Notes

Introduction

• Focus on sexual reproduction and development
• Distinction between male and female gametes:
  • Sperm (male): Motile, produced by males with a Y chromosome
  • Egg (female): Nutrient-rich, produced by females without a Y chromosome

Reproductive System Purposes

• Male: Produce and introduce sperm to the female body
• Female: Produce eggs, receive sperm, provide for fertilization, fetus harboring, nourishing offspring (including lactation)

Sex Organs Division

• Primary sex organs (gonads): Produce gametes
  • Males: Testes
  • Females: Ovaries
• Secondary sex organs: Necessary for reproduction
  • Males: Ducts, glands, penis
  • Females: Uterine tubes, uterus, vagina

Sex Characteristics

• Secondary sex characteristics: Distinguish sexes, influence attraction
  • Develop at puberty
  • Examples: Hair growth, voice pitch changes, muscle mass increase

Genetic Sex Determination

• Chromosomes: 23 pairs in human cells
  • Autosomes: First 22 pairs
  • Sex chromosomes: Last pair (XX or XY)
• Determination: Gender by sperm cell (X or Y carrying)

Sexual Differentiation and Development

• Early Development: Fetus is sexually undifferentiated
• Ducts: Mesonephric (male) and paramesonephric (female)
• SRY Gene: Codes for testes determining factor (TDF)
  • Leads to testes development, testosterone secretion, and mesonephric duct development
  • Secretes mullerian-inhibiting factor
• Female Development: Absence of androgens

Intersexuality and Variations

• Examples: SRY gene transfer, Androgen Insensitivity Syndrome (AIS)
• Gender vs Biological Sex: Psychological identity vs physical attributes

Male External Genitalia Development

• Genital Tubercle, Urogenital Folds, Labioscrotal Folds: Develop into different structures based on hormones
• Development Completion: By week 12

Gonadal Descent

• Testes Descent: Begins at 6 weeks; completes by seventh month
• Cryptorchidism: Undescended testes
• Ovaries Descent: Much lesser extent

Male Reproductive Anatomy

External Genitalia

• Scrotum: Skin, muscle, fibrous tissue pouch containing testes
  • Temperature regulation through dartos and cremaster muscles
  • Pampiniform plexus for blood temperature regulation

Testes

• Dual Role: Endocrine (hormones) and exocrine (sperm)
• Structure: Seminiferous tubules, interstitial cells, blood-testes barrier

Ducts and Glands

• Duct Pathway: Efferent ductules, epididymis, vas deferens, ejaculatory duct, urethra
• Glands: Seminal vesicles, prostate, bulbourethral gland

Hormonal Regulation

• HPT Axis: Hypothalamus, pituitary (FSH, LH), testes
• Andropause: Decline in testosterone with age

Spermatogenesis

• Process: Spermatogonia division, meiosis, spermiogenesis
• Sperm Structure: Head (nucleus, acrosome), tail (flagellum)

Semen and Male Sexual Response

• Semen Composition: Sperm, seminal plasma
• Male Sexual Response Phases: Excitement, plateau, orgasm, resolution

Erectile Dysfunction and Treatment

• Treatments: PDE inhibitors like Viagra

Sexually Transmitted Diseases

• Types: Bacterial (gonorrhea, chlamydia, syphilis), Viral (herpes, HPV, hepatitis)