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.