Textbook

• The homeostatic control of the water potential of the blood is....

  Osmoregulation
• Structure of the kidney

  • Fibrous capsule
  • Cortex
  • Medulla
  • Renal pelvis
  • ureter
  • renal artery
  • renal vein
• Fibrous capsule

  An outer membrane that protects the kidney
• Cortex


  a lighter coloured region made up of renal/Bowman's capsules, convoluted tubules and blood vessels
• Medulla


  a darker coloured inner region made up of loops of Henle, collecting ducts and blood vessels
• Renal pelvis 


  a funnel-shaped cavity that collects urine into the ureter
• Ureter


  a tube that carries urine to the bladder
• Renal artery


  supplies the kidney with blood from the heart via the aorta
• Renal vein


  returns blood to the heat via the vena cava
• Structure of the nephron

  • Renal/Bowman's capsule
  • Proximal convoluted tubule
  • Loop of Henle
  • Distal convoluted tubule
  • Collecting duct
• Blood vessels associated with each nephron

  • Afferent arteriole
  • Glomerulus
  • Efferent arteriole
  • Blood capillaries
• Renal/Bowman's capsule


  The closed end at the start of the nephron. It is cup-shaped and surrounds a mass of blood capillaries known as the glomerulus. The inner layer of the Bowman's capsule is made up of specialised cells called podocytes
• Proximal convoluted tubule (PCT)


  A series of loops surrounded by blood capillaries. Its walls are made up of epithelial cells which have microvilli
• Loop of Henle


  A long, hairpin loop that extends from the cortex into the medulla of the kidney and back again. It is surrounded by blood capillaries
• Distal convoluted tubule (DCT)

  A series of loops surrounded by capillaries. Its walls are made of epithelial cells, but it is surrounded by fewer capillaries than the proximal tubule
• Collecting duct


  A tube into which a number of distal convoluted tubules form a number of nephrons empty. It is lined by epithelial cells and becomes increasingly wide as it empties into the pelvis of the kidney
• Afferent arteriole


  A tiny vessel that ultimately arises from the renal artery and supplies the nephron with blood. The afferent arteriole enters the renal capsule of the nephron where it forms
• The nephron carries out its role of osmoregulation in a series of stages

  1. The formation of glomerular filtrate by ultrafiltration
  2. Reabsorption of glucose and water by the proximal convoluted tubule
  3. Maintenance of a gradient of sodium ions in the medulla by the loop of Henle
  4. Reabsorption of water by the distal convoluted tubule and collecting ducts