AUBF

• Kidney


  A bean-shaped organ about the size of the wrist, located on the posterior abdominal or behind the abdomen
• Primary functions of the kidney

  • Excretion
  • Regulation of blood volume and pressure
  • Regulation of solute concentration
  • Red blood cell synthesis
• Function of the kidney in erythropoiesis

  Production of Erythropoietin protein
• Triggers the release of EPO

  Hypoxia
• Function of kidney in Vitamin D synthesis

  Produces the biologically active form of vitamin D3, 1,25-dihydroxycholecalciferol
• Vitamin D


  Also known as Cholecalciferol
• Main functions of the kidney

  • Glomerular filtration
  • Tubular reabsorption
  • Tubular secretion
• Parts of the kidney

  • Renal cortex
  • Renal medulla
  • Renal artery
  • Renal vein
  • Renal pelvis
• Nephron


  Basic unit of the kidney, where the majority of processes in the kidney happen
• There are approximately 1-1.5 million nephrons per kidney
• Types of nephrons


  • Cortical
  • Juxtamedullary
• Cortical nephrons


  • Make up 85% of nephrons
  • Situated at the renal cortex
  • Involved in removal of waste products and reabsorption of nutrients
• Juxtamedullary nephrons


  • Final concentration of urine
  • Have a longer Loop of Henle extending to the renal medulla
• 25% of the blood pumped enters the kidneys
• Renal Blood Flow (RBF) is 1200 mL/min
• Renal Plasma Flow (RPF) ranges from 600-700 mL/min
• Components of centrifugated blood

  • Packed RBC
  • WBC
  • Platelets
  • Buffy coat
  • Plasma
• Plasma accounts for at least 55% of centrifugated blood
• Plasma comprises 55% of the blood, so 1200 x 55% = 660
• Blood will enter


  Renal artery
• Blood from renal artery goes to

  Afferent arterioles
• Blood enters the capillaries of the nephron through

  Afferent arteriole
• Blood from afferent arterioles goes to

  Glomerulus
• Glomerulus


  • Nonselective filter of plasma substances <70kD (kilodaltons)
  • Substances greater than 70kD will not be allowed to pass through
  • Located within the Bowman’s capsule
• Blood after the glomerulus goes to

  Efferent arterioles
• Blood from efferent arteriole enters

  Peritubular capillaries
• Peritubular capillaries


  • Very small blood vessels located in the kidneys
• When blood converges with deoxygenated blood, it is called


  Vasa recta
• Vasa recta


  • Interchange of capillaries carrying oxygenated and deoxygenated blood
  • Crossing point of the blood
  • Location where exchange of oxygen, filtration, and absorption of substances happen
• Renal blood flow


  • Renal artery
  • Afferent arteriole
  • Glomerulus
  • Efferent arteriole
  • Peritubular capillaries
  • Vasa recta
  • Renal vein
• Urine composition


  • 95% water
  • 5% solutes
  • 35g organic solutes – UREA, Creatinine, Uric Acid
• 4 non-protein nitrogen compounds are Ammonia, Creatinine, BUA, BUN
• Urea is the majority component of BUN/Urea since it has the highest concentration in blood
• Urea is a product of protein and amino acid metabolism
• Creatinine is the end product of muscle metabolism
• Methionine, lysine, arginine are 3 amino acids that synthesize creatinine
• Uric acid is the end product of purine metabolism
• Ammonia is not included in non-protein nitrogen compounds because it is freely reabsorbed by the kidney
• 25g inorganic solutes in urine include Cl > Na > P
• Chloride is the major inorganic solute excreted by urine