Urinary System Anatomy Overview

Urinary System Anatomy Overview

• The urinary system maintains normal blood and tissue fluid composition, volume, and pH by removing substances that disrupt balance.
• It regulates blood volume by filtering and conserving water and other substances.
• Electrolyte balance is regulated via excretion or conservation of minerals.
• Acid-base balance relies on excretion or conservation of ions like H+ and HCO₃⁻.

Urinary System Organs

• Kidneys (2): Paired organs located in the posterior body wall, retroperitoneal.
• Ureters (2): Carry urine from kidneys to the bladder.
• Urinary Bladder: Stores urine.
• Urethra: Transports urine from the bladder to the outside of the body.

Kidney Location and Protection

• Kidneys are retroperitoneal, meaning located behind the peritoneum.
• They are protected by layers of connective tissue:
  • Renal capsule: A fibrous covering providing protection and maintaining kidney shape.
  • Adipose capsule (perirenal fat): Cushions and stabilizes the kidneys.
  • Renal fascia: Holds the kidneys in place, in contact with the muscles of the posterior abdominal wall.

Kidney Structure

• Renal cortex: Outer layer containing nephrons.
• Renal medulla: Inner layer containing renal pyramids with nephrons.
• Renal pelvis: A funnel-shaped structure collecting urine and connecting to the ureters.

Nephron

• Functional units: Microscopic filtering structures within the kidney.
• Two parts:
  • Renal corpuscle: Globe-shaped structure with filtering capillaries (glomerulus).
  • Renal tubule: Long, tubular structure reabsorbing needed components.

Urine Formation and Flow

• Urine drains from the minor calyx to major calyx and renal pelvis, eventually entering ureters.
• Urine is moved through the ureters and stored in the bladder by peristaltic action.
• The internal and external urethral sphincters control urine release.

Blood Supply to Kidneys

• Receiving approximately one-quarter of the total cardiac output, the kidneys receive blood via renal arteries.
• Blood is filtered through the glomerulus; then transported through the efferent arterioles to peritubular capillaries, before returning to the inferior vena cava via smaller blood vessels (interlobar, arcuate, interlobular veins).

Ureter Structure and Function

• Ureters are muscular tubes about 25-30 cm long in adults.
• The ureters carry urine from the renal pelvis to the urinary bladder.
• Peristaltic waves transport urine through the ureters.
• Bladder pressure regulates opening between ureters and bladder.

Bladder Structure and Function

• Hollow, distensible organ located in the pelvic cavity.
• The trigone is the triangular region at the base of the bladder where ureters join.
• The bladder stores urine until urination.

Urethra Structure and Function

• The final part of the urinary tract. It drains urine from the bladder to the exterior.
• Different lengths and functions in males and females:
  • Female: Shorter (4 cm), primary function: urine removal.
  • Male: Longer (20 cm), dual function in urination and ejaculation.

Male vs. Female Anatomy Differences

• Male urethra passes through prostate.
• Longer male urethra.
• Different locations in the pelvic region versus females.

This quiz covers the anatomy of the urinary system, including the role of kidneys, ureters, bladder, and urethra. Learn how this system maintains fluid balance, electrolyte levels, and acid-base equilibrium in the body. Test your knowledge on the structure and function of these vital organs.