Biology

• Ultrafiltration

  1. Blood from the renal artery enters the glomerulus

  2. Water, urea, salts and glucose are forced into the Bowman's capsule

  3. Blood cells and large proteins cannot pass through
• Selective reabsorption


  1. In the tubule, some salt and water and all the glucose move out of the nephron by active transport

  2. These substances are reabsorbed back into the blood capillary
• Loop of Henlé

  • Permeable to water but not salt
  • Water is drawn out of the filtrate in the nephron by osmosis because of the low water potential of the medulla tissue fluid
• Collecting duct


  The remaining substances move into the collecting duct, forming urine