1. Multiple Functions of the Kidneys

• What is one important function of the kidneys?

  To rid the body of waste materials
• Why is the control of body fluid volume critical?

  It maintains a stable internal environment
• How do kidneys maintain electrolyte balance?

  By regulating intake and output of electrolytes
• What is the process by which kidneys clear unwanted substances?

  By filtering plasma and excreting urine
• What are the homeostatic functions of the kidneys?

  • Excretion of metabolic waste products
  • Regulation of water and electrolyte balances
  • Regulation of body fluid osmolality
  • Regulation of arterial pressure
  • Regulation of acid-base balance
  • Regulation of erythrocyte production
  • Secretion and metabolism of hormones
  • Gluconeogenesis
• What waste product is produced from amino acid metabolism?

  Urea
• What is creatinine a byproduct of?

  Muscle creatine metabolism
• Why must metabolic waste products be eliminated quickly?

  To prevent accumulation in the body
• How do kidneys respond to increased sodium intake?

  By increasing renal sodium excretion
• What happens during renal adaptation to high sodium intake?

  Sodium accumulates and triggers hormonal changes
• What is the maximum sodium intake kidneys can handle?

  1500 mEq/day
• How do kidneys regulate arterial pressure?

  By excreting sodium and water
• What hormone do kidneys secrete to stimulate red blood cell production?

  Erythropoietin
• What stimulates erythropoietin secretion?

  Hypoxia
• What is the active form of vitamin D produced by the kidneys?

  1,25-dihydroxyvitamin D3
• What is gluconeogenesis?

  Synthesis of glucose from amino acids
• What happens with chronic kidney disease?

  Homeostatic functions are disrupted
• What can occur with complete renal failure?

  Accumulation of potassium and acids
• What are the consequences of severe kidney disease?

  • Severe anemia due to low erythropoietin
  • Accumulation of potassium and acids
  • Disruption of fluid and electrolyte balance
  • Risk of death without clinical intervention