Renal Phys 1

• highly vascularized, allows fluids to filter

  the kidneys
• regulation of water, inorganic ion balance, and acid-base balance (in cooperation with the lungs)


  function of the kidneys
• removal of metabolic waste products from the blood and their excretion in the urine (ex: urea, uric acid, bilirubin)


  function of the kidneys
• by-products of protein breakdown

  urea and uric acid
• gives the yellow color to urine, brown color to feces, and green color to bile

  bilirubin
• removal of foreign chemicals from the blood and their excretion in the urine

  function of the kidneys
• gluconeogenesis (along with the liver)


  function of the kidneys
• what is gluconeogenesis?


  creation of new glucose from non glucose substrates (amino acids & lipids)
• production of the hormones/enzymes: erythropoietin, renin, and activated vitamin D


  function of the kidneys
• what does erythropoietin do?

  stimulates the production of RBC's, which affects oxygen content and blood viscosity
• what does renin do?

  this is an enzyme that controls the formation of angiotesin, which influences blood pressure and sodium balance
• what is the concise description of converting 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D, which influences calcium balance?

  the activation of vitamin D by the kidneys
• where are the kidneys located?

  at the superior and posterior aspect of the abdominal cavity (top/back)

  they are retroperitoneal
• what does retroperitoneal mean?

  located outside the peritoneal (organ) sac
• what is the functional unit of the kidney? (there are ~1 million per kidney)

  nephron
• path of "dirty" blood

  renal artery -> cortex -> nephron -> medulla -> calyx -> renal pelvis -> ureter -> urinary bladder
• the nephron tubules

  1.) Bowman's Capsule

  2.) Proximal Convoluted Tubule

  3.) Loop of Henle

  • descending
  • ascending

  4.) Distal Convoluted Tubule

  5.) Collecting Duct

  • cortical
  • medullary
• the nephron blood supply

  renal artery

  afferent arteriole

  glomerular capillaries (glomerulus)

  efferent arterioles

  peritubular capillaries (vasa recta)

  renal vein
• the renal corpuscle

  glomerular capillaries + bowman's capsule
• two types of nephrons

  juxtamedullary and cortical
• long loops of Henle


  juxtamedullary
• close to the medulla


  juxtamedullary
• generates gradients in medulla important for H2O reabsorption


  juxtamedullary
• 15% of nephrons


  juxtamedullary
• where the peritubular capillaries help generate the gradient in medulla

  juxtamedullary
• 85% of nephrons


  cortical
• short loops of Henle


  cortical
• do not contribute to gradient in medulla


  cortical
• outer layer of kidney


  renal cortex
• contains renal corpuscles of all nephrons


  renal cortex
• group of many collecting ducts

  renal pyramid
• contains proximal and distal tubules of all nephrons


  renal cortex
• contains cortical nephrons


  renal cortex
• inner layer

  renal medulla
• contains long Loops of Henle from juxtamedullary nephrons


  renal medulla
• contains medullary portion of the collecting ducts

  renal medulla
• allows the kidney to control and regulate blood pressure; region made of three different cell types


  the juxtaglomerular apparatus (JGA)
• the three cell types that make up the JGA

  juxtaglomerular cells (aka granular cells)

  macula densa

  sympathetic nerve fiber
• surrounds afferent arteriole

  granular cells
• synthesize, store, and secrete renin

  granular cells