Medicine & USMLE

Kidney Overview

  1. Renin
  2. Angiotensin II
  3. Aldosterone
  4. ADH
  5. RAAS System
  6. Kidney Overview
  7. Nephron Structure
  8. Glomerulus
  9. Proximal Tubule
  10. Loop of Henle
  11. Distal Tubule
  12. Collecting Duct

  • Kidney Overview
    • The kidneys filter blood to excrete waste as urine and maintain appropriate solute and water concentrations throughout the body. 
    • Mechanism (broadly)
      • Filtration
      • Reabsorption
      • The kidneys throw out almost everything indiscriminately (filtration), then selectively taking back what it wants (reabsorption)
    • Roles
      • Waste removal
        • Elimination of nitrogenous waste, including urea, uric acid, ammonia, and phosphate in urine
      • Blood volume (pressure) control
        • via solute reabsorption
          • Na+ reabsorption is coupled to water (and Cl-), thereby affecting blood volume
        • Regulated by RAAS system
          • Renin released in response to low blood pressure
      • Blood osmolality control
        • via water reabsorption
          • ADH regulates water reabsorption in collecting ducts
      • Acid/base balance
        • via bicarbonate reabsorption and H+ (acid) secretion
    • Composed of:
      • outer cortex
      • inner medulla 
        • More “salty”, or higher in osmolarity
    • Functional unit is the nephron