Kidney

• Kidneys filter blood to remove waste products from the body.

  
• what are the components of the kidney

  • fibrous capsule
  • cortex
  • pyramid
  • medulla
  • pelvis
  • ureter
  • renal artery and vein
• cortex


  • darker outer Kater
  • where filtration occurs
  • very dense capillary network
• medulla


  • lighter in colour
  • contains tubules of the nephrons that form the pyramids and collecting ducts
• pelvis


  • the central chamber where urine collects before passing out down the ureter
• what is a nephron


  small structures that act as filtering units
• structure of nephrons


  • Bowman's capsule
  • proximal convoluted tubule (PCT)
  • loop of Henle
  • distal convoluted tubule (DCT)
  • collecting duct
• structure of Bowman's capsule


  cup shaped structure that contains the glomerulus

  • glomerulus is a tangle of capillaries

  the wall of Bowman's contains podocytes, which act as additional filters

  also extensions called pedicels wrap around capillaries, ensuring that unwanted cells do not get to the tubule (cells, platelets, plasma proteins)
• proximal convoluted tubule (PCT)


  • the first coiled region after Bowman's
  • found in cortex
  • where reabsorption occurs
• structure of Loop of Henle


  long loop of tubule that creates region wit high solute concentration in tissue fluid in medulla

  2 limbs

  • descending - runs down from cortex through to medulla, to hairpin bend
  • ascending - runs back up from hairpin bend, toward DCT
• distal convoluted tubule


  second twisted region where fine-tuning of water balance occurs

  permeability of water varies due to levels of ADH

  • further ion and pH balance regulation occurs
• collecting duct


  urine passes down through medulla to pelvis

  • more fine-tuning of water balance
  • walls are also sensitive to ADH
• nephrons have a network of capillaries around them, leading to venues, then to the renal vein