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Male Reproductive System

Overview of the Reproductive System

  • Overall function: Produce offspring
    • Male:
    • Produce sperm
    • Deliver sperm to female
    • Female:
    • Produce eggs
    • Receive sperm
    • Provide site for fertilization
    • Harbor and nourish fetus
    • Give birth
    • Nourish offspring

Primary Sex Organs

  • Function: Produce gametes and supply genetic material from each parent
    • Female: Ovary (produces eggs)
    • Male: Testis (produces sperm)

Secondary Sex Organs

  • Function: Support reproductive processes
    • Male: Spermatic ducts, glands, and penis (storage, maintenance, and conveyance of sperm)
    • Female: Uterine tubes, uterus, vagina (unite sperm and egg, harbor fetus, deliver offspring)

Scrotum

  • Contains: Testes
  • Median septum: Divides scrotum into left and right compartments
  • Spermatic cord:
    • Fibrous connective tissue channel containing ductus deferens, neurovasculature, and lymphatics
    • Travels through inguinal canal

Scrotal Temperature Control

  • Importance: Sperm production requires a cooler environment
  • Cremaster muscle:
    • Continuation of internal oblique muscle
    • Contracts/relaxes to change position of testes
  • Dartos fascia:
    • Subcutaneous smooth muscle that holds testes against the body
    • Alters scrotal surface area to conserve/release heat
  • Pampiniform plexus:
    • A venous network surrounding the testicular artery acting as a countercurrent heat exchanger

Testes

  • Function: Produce sperm and sex hormones
  • Tunica vaginalis:
    • Double layer of connective tissue derived from the abdominal peritoneum
  • Tunica albuginea:
    • Fibrous capsule that projects into testis, dividing it into lobules

Testicular Lobules

  • Components:
    • Interstitial endocrine cells: Produce testosterone
    • Seminiferous tubules: Site of sperm production
    • Germ cells: Develop into sperm with the support of nurse cells (provide nutrients, remove waste, secrete proteins)

Spermatic Ducts

  • Efferent ductules:
    • Transmit sperm to epididymis (ciliated)
  • Epididymis:
    • Site of sperm maturation and storage; single coiled duct; sperm may remain viable for approximately 60 days
  • Ductus deferens:
    • Carries sperm into pelvic cavity; ampulla (terminal portion) empties into ejaculatory duct

Accessory Glands

  • Seminal vesicles:
    • Contribute about 60% of seminal fluid (contains glucose, prostaglandins, alkaline compounds)
  • Prostate:
    • Contributes about 30% of seminal fluid (contains spermine, prostate-specific antigen)
  • Bulbourethral glands:
    • Provides lubrication and neutralizes residual acidity of urine

Common Conditions

Benign Prostatic Hyperplasia (BPH)
  • Most common prostate condition affecting 90% of males by age 85
  • Symptoms:
    • Increased size of prostate compressing urethra
    • Difficulty initiating/completing urination, potential pain during urination or ejaculation
    • Untreated, may lead to UTIs or kidney damage

Testicular Circulation

  • Testicular artery:
    • Very low pressure (no pulse)
  • Pampiniform plexus:
    • Merges to form testicular veins (right to inferior vena cava, left to left renal vein)

Blood-Testis Barrier (BTB)

  • Definition: Boundary formed by tight junctions between nurse cells
  • Function: Protects developing sperm and allows nurse cells to control the extracellular environment

Descent of the Testes

  • Process wherein testes develop in abdomen and descend into the scrotum, carried along by the gubernaculum through the inguinal canal

Inguinal Canal and Hernias

  • Connection: Between abdominal cavity and external genitalia; can experience hernias where intestines protrude into the canal

Penis Anatomy

  • Structure: Divided into root (internal portion), shaft, glans (ends at urethral orifice)
  • Shaft Composition:
    • Erectile tissue (trabeculae and lacunae)
    • Contains corpus spongiosum (encloses urethra) and corpora cavernosa (surrounded by tunica albuginea)

Penis Circulation

  • Supplied by branches of internal pudendal arteries; drained by various venous plexus

Conclusion

  • Recap on the complexity and functionality of the male reproductive system, emphasizing its critical role in reproduction and various potential health challenges that may arise.