KIDNEYS

• The kidneys are situated in a retroperitoneal position, at the level of the T12 to L3 vertebrae.
• The right kidney is slightly lower than the left because of the liver, and is about 12 cm long and 6 cm wide.
• Renal hilum - medial indentation where several structures enter or exit the kidney
• 3 protective layers of the kidney (inner to outer):

  • Fibrous capsule
  • Perirenal fat capsule
  • Renal fascia
• 3 regions of the kidney:

  • Renal cortex - outer region
  • Renal medulla - deeper region
  • Renal pelvis - medial region; flat, funnel-shaped tube

  2 parts of renal medulla:

  • Renal pyramids - triangular regions of tissue
  • Renal columns - separates pyramids
• Nephrons - functional units of the kidney; 1 to 1.5 million in each kidney
• 2 types of nephrons:

  • Cortical nephrons - 85% of nephrons; removes waste products and reabsorbs nutrients
  • Juxtamedullary nephrons - regulates concentration of urine
• Functions of the nephrons:

  • Renal blood flow
  • Glomerular filtration
  • Tubular reabsorption
  • Tubular secretion