Lecture Notes: Urinary System and Related Structures

Overview

• Focus on anatomical structures rather than physiological details.
• Urine formation process: nephrons -> collecting ducts -> renal pelvis -> ureter -> urinary bladder -> urethra.

Ureters

• Tubular organs, ~25 cm long.
• Transport urine from kidneys to bladder, beginning at the renal pelvis.
• Empty into the posterior portion of the urinary bladder.
• Composed of:
  • Mucosal coat: Transitional epithelium.
  • Muscular layer: Peristalsis movement.
  • Fibrous coat: Anchors in place.
• Obstructions: Kidney stones (renal calculi), treated via strong peristaltic waves.

Uretero-Renal Reflex

• Occurs when a blockage in the ureter decreases urine production in the affected kidney.
• Prevents kidney failure or ureter rupture.

Chronic Glomerulonephritis

• Inflammation of glomerular capillaries.
• Symptoms: Hypertension, proteinuria, hematuria, decreased blood proteins.
• Leads to end-stage renal disease; treatment includes hemodialysis or kidney transplant.

Kidney Stones

• Composed of uric acid, calcium oxalate/phosphate, magnesium phosphate.
• Form in collecting ducts or renal pelvis, causing severe pain.
• Majority pass naturally; others treated by lithotripsy or surgery.
• Genetic predisposition to stone formation.

Urinary Bladder

• Hollow, distensible organ storing urine.
• Components: Two ureters and one urethra form the trigone.
• Composed of four layers:
  • Inner mucosal coat: Transitional epithelium.
  • Submucosal coat: Connective tissue.
  • Muscular coat: Detrusor muscle, internal urethral sphincter.
  • Outer serous coat.
• Pregnancy can reduce bladder capacity, influencing urination frequency.

Urethra Structure

Female Urethra

• ~4 cm long, anterior to vaginal opening.

Male Urethra

• ~19.5 cm long, used for urination and reproduction.
• Three sections:
  1. Prostatic urethra.
  2. Membranous urethra.
  3. Spongy urethra.
• Ends at external orifice in the penis.

Urination (Micturition)

• Process: Reflex contraction of detrusor muscle and relaxation of urethral sphincters.
• Bladder capacity: Up to 600 mL; urge begins at 150 mL.
• Controlled by micturition reflex center in the sacral spinal cord.
• Issues: Incontinence, nocturnal enuresis.

Developmental Abnormalities & Urinalysis

• Abnormalities can affect various urinary structures.
• Urinalysis diagnoses disorders, checks for drugs; e.g., glucose in urine for diabetes.

Age-Related Changes

• Kidneys become less efficient in filtration and waste removal.
• Urinary bladder, ureter, urethra lose elasticity.
• Decreased kidney function leads to various inefficiencies and potential incontinence.