GCSE Biology 3

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GCSE Biology 3
2013-04-18 18:20:38

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  1. where are the kidneys located in our bodies
  2. Show where nephrons are in the kidneys
  3. Show an enlarged view of a nephron
  4. Nephrons are
    Filtration units in the kidney
  5. What stages occur in the kidney
    • Ultrafiltration 
    • reabsorption 
    • release of waste
  6. Explain ultrafiltration
    • A highs pressure is built up which squeezes water , urea , ions and sugar out of the blood and into the bowman's capsule 
    • the membranes between the blood vessels and the bowman's capsule act like filters so big molecules like protein ands and red blood cells are not squeezed out . They stay in the blood
  7. Explain reabsorption
    • As the liquid flows along the nephron , useful substances are reabsorbed back into the blood : 
    • 1) all the sugar is reabsorbed this involves the process of active transport against the concentration gradient
    • 2) sufficient ions are reabsorbed . Excess ions are not . Active transport is needed 
    • 3) sufficient water is reabsorbed
  8. Explain release of wastes
    The remaining substances including urea continue out the he nephron , into the ureter and down the bladder as urine
  9. The kidneys remove
    • waste substances from the blood
    • 1) if the kidneys didn't work properly , waste substances build up In the blood and you lose your ability to control the levels of ions and water in your body . eventually this leads to death 
    • 2) people with kidney failure can be kept alive by having dialysis treatment - where the machines do the job of the kidneys . Or they have a kidney transplant
  10. Dialysis machines
    Filter the blood
  11. Using a diagram explain how a dialysis machine works
    • dialysis has to be done regularly to keep the concentrations of dissolved substances in the blood at normal levels , and toremove waste   substances  
    • in a dialysis machine the persons blood flows alongside a selectively permeable barrier , surrounded bY dialysis fluid . Its permeable to things like ions and waste substances , but not big molecules like protein (just like membranes in the kidney) 
    • the dialysis fluid has the same concentration of dissolved ions and glucose as healthy blood 
    • this means that useful dissolved ions and glucose Wont be lost from the blood during dialysis
    • only waste substances such as urea and excess ions and water diffuse across the Barrier
  12. Many patients with kidney failure have to have dialysis