Lecture Notes: Kidney and Nephron Anatomy

Introduction

• Lecture by Earth, RN
• Focus on kidney and nephron anatomy
• Part of the INLEX review series on the renal system

Overview of Kidneys

• Number of Kidneys: Two (right and left)
  • Right kidney is lower due to the liver's position
• Functions:
  • Filtration, absorption, secretion, and excretion
  • Produce filtrate, which becomes urine
  • Blood supply via renal artery and renal vein
  • Urine pathway: kidney ➔ ureter ➔ bladder ➔ urethra

Kidney Anatomy

• Renal Capsule: Protective outer layer
• Renal Cortex: Outer layer
• Renal Medulla: Inner layer
  • Contains renal pyramids, which contain parts of the nephron
• Renal Pyramids
  • Striped appearance due to nephron arrangement

Renal Drainage Pathway

• Urine flows from renal pyramids to:
  • Renal Papilla ➔ Calyces (minor and major) ➔ Renal Pelvis ➔ Ureter ➔ Bladder ➔ Urethra
• Renal Columns: Areas between pyramids containing blood vessels

Nephron Anatomy

• Functional Unit of Kidney
  • Each kidney contains millions
• Parts of a Nephron:
  • Renal Corpuscle: Filtration
    • Includes Bowman's capsule and glomerulus
  • Renal Tubule: Reabsorption and secretion

Nephron Blood Supply

• Afferent Arteriole: Brings blood to glomerulus
• Glomerulus: Network of capillaries for filtration
• Efferent Arteriole: Carries blood away, forms peritubular capillaries
  • Peritubular Capillaries: Surround renal tubule for exchange
  • Vasa Recta: Associated with the loop of Henle

Filtration and Urine Formation

• Filtrate Components: Water, ions, waste
• Reabsorption and Secretion:
  • Reabsorption: Movement back into blood
  • Secretion: Movement from blood into tubule

Nephron Segments

• Proximal Convoluted Tubule: Major site of reabsorption
• Loop of Henle
  • Descending limb: Water reabsorption
  • Ascending limb: Ion transport
  • Located in the hypertonic renal medulla
• Distal Convoluted Tubule: Further reabsorption and secretion
• Collecting Duct: Final concentration of urine

Urine Flow

• From collecting duct through renal papilla ➔ calyces ➔ renal pelvis ➔ ureter ➔ bladder ➔ urethra

Conclusion

• Importance of nephron in urine formation
• Reminder to watch the next video on nephron physiology
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