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Anatomy of the Kidneys

Jul 26, 2024

Anatomy of the Kidneys Lecture Notes

Urinary System Overview

  • Components: Kidneys, Ureter, Urinary Bladder, Urethra
  • Goal: Cover the anatomy of each structure starting with the kidneys

Kidney Functions

  1. Plasma Filtration
    • Nephron, specifically the Renal Corpuscle, filtrates plasma
  2. Excretion of Waste Products
    • Metabolic waste: ammonia, uric acid, urea, creatine, creatinine, amino acids
    • Important for removing potentially dangerous waste products
  3. Acid-Base Homeostasis
    • Maintains blood pH between 7.35 to 7.45
    • Regulated through lungs and kidneys
  4. Other Functions
    • Hormone production (e.g., erythropoietin)
    • Vitamin D metabolism (activates vitamin D)

Kidney Anatomy

External Structures

  • Size: 120-200 grams, 10-13 cm long, 5-6 cm wide, 4 cm thick
  • Poles: Inferior and Superior (with suprarenal gland)
  • Margins: Lateral and Medial
    • Hilum: Entry/exit point for blood vessels, nerves, lymph vessels, ureter

Coverings

  • Layers:
    1. Fibrous Capsule: Dense protective fibers
    2. Adipose Capsule (Perinephric Fat): Thicker posteriorly, protects from concussion and cold
    3. Renal Fascia: Anterior (Fascia of Toldt) and Posterior Layer (Layer of Zuckerkandl)

Internal Structures

Renal Cortex

  • Location: Outer layer
  • Composition: Renal corpuscle, proximal and distal convoluted tubules
  • Extensions: Renal columns
  • Nephrons: 1 to 1.5 million per kidney

Renal Medulla

  • Structure: Renal pyramids (7-18 per kidney)
    • Components: Loop of Henle, collecting duct
    • Renal Papilla: Apex of pyramids, leads to minor calyces
    • Renal Medullary Rays: Parts of medulla extending towards cortex

Renal Sinus

  • Contents: Renal pelvis and calyces, filled with renal sinus fat

Urine Flow Pathway

  1. Minor Calyces
  2. Major Calyces
  3. Renal Pelvis
  4. Ureter

Nephron Anatomy

Renal Corpuscle

  • Components: Glomerulus (capillary loops), Glomerular capsule
    • Afferent arteriole: Blood arrives
    • Efferent arteriole: Blood exits

Tubular System

  1. Proximal Convoluted Tube
  2. Loop of Henle (in medulla)
    • Descending and Ascending parts
  3. Distal Convoluted Tube
  4. Collecting Ducts
    • Fuse into papillary ducts, open into minor calyces

Conclusion

  • Next topic: Anatomy of the Ureter, Urinary Bladder, and Urethra (male and female)

Full transcript