Urinary System Overview Lecture Notes

Introduction

• Urinary system is one of the simplest systems.
• Components:
  • Kidneys: Produce urine.
  • Ureters: Tubes from kidneys to bladder.
  • Urinary Bladder: Storage for urine.
  • Urethra: Tube to the outside of the body.

Functions of the Urinary System

• Excretion: Remove organic wastes from body fluids.
  • Includes urea from deamination processes.
• Homeostatic Regulation:
  • Regulate blood plasma volume and solute levels.
  • Maintain blood pressure, plasma ion concentration, and blood pH.
  • Conserve nutrients and assist in detoxification.

Anatomy of the Urinary System

• Kidneys:

  • Two kidneys; left is higher due to liver positioning.
  • Adrenal gland on top for adrenaline release.
  • Covered by renal capsule, adipose tissue, and renal fascia.
  • Adult kidney size: 10 cm long, 150 grams.
  • Hilum: Indentation where blood vessels and urethra enter/exit.

• Renal Structures:

  • Renal Capsule: Outer covering of the kidney.
  • Renal Cortex: Outer layer, involved in urine production.
  • Renal Medulla: Contains renal pyramids (6-18 per kidney).
    • Renal Pyramids: Darker tissue, contains renal papilla.
  • Renal Columns: Between pyramids, cortical tissue.
  • Renal Lobe: Half cortex, half column, and pyramid.

Blood Supply to the Kidneys

• Renal Artery: Delivers blood to kidney.
  • Splits into segmental arteries → interlobar arteries → arcuate arteries → interlobular arteries.
  • Afferent Arterioles: Lead to glomerulus (filtration site).
  • Efferent Arterioles: Lead from glomerulus to peritubular capillaries.
  • Blood exits via venules → interlobular veins → arcuate veins → interlobar veins → renal vein.

Urine Formation

• Detailed in next session.

Conclusion

• Detailed exploration of kidney anatomy.
• Next session will cover urine formation mechanisms.