Human Anatomy - Urinary System Flashcards

Urinary System Components

• Comprises kidneys, ureters, bladder, and urethra, along with associated ducts.
• Kidneys are positioned retroperitoneally, lying high on the posterior abdominal wall on either side of the vertebral column.

Kidney Structure

• Renal Capsule: Protective layer covering the kidneys.
• Renal Cortex: Outer layer that houses glomeruli, where initial filtration occurs.
• Renal Medulla: Internal region containing renal pyramids and columns; balances ions in the nephron loop.

Urine Production Pathway

• Urine flows through renal pyramids which lack blood vessels.
• Blood is filtered in nephron units, then travels through renal columns.
• Renal papilla marks the apex of the renal pyramid.
• Minor Calyx: Collects urine from papilla before entering the major calyx.
• Major Calyx: Collects urine that culminates in the renal pelvis.

Blood Vessels and Filtration

• Renal arteries branch into smaller vessels, filtering blood within renal cortex glomeruli.
• Glomerulus: Primary site for blood filtration; most urine components are separated here.
• Capillary Network: Enables oxygenation and nutrient exchange.

Kidney Function and Fluid Handling

• Processes about 180 liters of fluid daily with only 2% excreted as urine.
• Nephrons act as the kidneys' filtering units, purifying blood and expelling wastes.
• Collecting Duct: Final site for urine concentration; urine is irreversibly modified here.

Kidney Regions' Characteristics

• Renal cortex is more hydrated, while renal medulla is saltier.
• The ascending limb of the nephron loop requires energy for salt transport against osmotic gradient.

Urine Composition

• Composed of 95% water, and typically contains urea, uric acid, creatinine, trace amino acids, and varying electrolytes.

Ureters and Bladder

• Ureters transport urine from kidneys to bladder; muscular ducts located distally to renal pelvis.
• Urinary bladder is a muscular reservoir that can expand and contract, enters through ureters and exits via urethra.

Urethra and Elimination Pathway

• Tube leading urine from bladder to the exterior; extends from bladder base.
• Ureteric orifices are located at bladder trigone corners, marking distinct embryological origins.

Detrusor Muscle and Trigone

• Detrusor Muscle: The bladder's muscular lining that enables contraction during urination.
• Trigone: Triangular area at the bladder's base with openings at each angle; structural site for urine entry.

Kidney Stones

• Form from crystallization of calcium, magnesium, or salts; can cause severe pain as they pass through the ureters.
• Common obstruction points include:
  • Junction of ureters and renal pelvis
  • Ureters crossing pelvic inlet
  • Passage through bladder wall.

Steps for Urine Elimination

• Involves sequence: Nephrons -> Collecting ducts -> Renal papillae -> Minor calyces -> Major calyces -> Renal pelvis -> Ureters -> Urinary bladder -> Urethra.