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  • Excretion
    • Metabolic Waste
      • Carbon dioxide It is a product of aerobic respiration
        • It is removed through the lungs when we breathe out
      • Urea is produced in the liver when excess amino acids are broken down
        • kidneys remove it from the blood and make urine - which is temporarily stored in the bladder
    • Water Balance
      • We take in water through food and drink, also we get some when we respire
      • We lose water in sweat, faeces, urine and when we breathe out. 
      • For our cells to work properly, our water and mineral ion content has to be maintained at the correct level 
        • If the ion and water content was to change to much water would be going in and out of the cells, then damaging them.
      • Our body must control the the water we take in and the water we lose. This is done by the kidneys
        • The kidneys maintain our water balance by producing urine of different concentrations
    • Kidney Dialysis/ Transplants
      • Dialysis
        • Patients are connected to a dialysis machine which acts as an artificial kidney to remove most of the urea and restore/maintain the water and ion balance of the blood.
        • Haemodialysis - A machine takes over the function of the kidneys
          • Blood is passed through a system of tubing made from a cellulose like substance that is partially permiable 
          • The tubing is surrounded by dialysis fluid - this contains glucose, sodium,useful minerals and has similar concentrations to normal blood plasma
        • Advantages/ dissadvantages
          • Available to all kidney patients
          • No need for immune-suppressant drugs
          • Patient must limit their salt and protein intake between dialysis sessions
          • Expensive for the NHS
          • Regular dialysis sessions – impacts on the patient’s lifestyle
      • Transplants
        • The main problem to kidney transplants is rejection.
          • Precautions against rejection
            • Tissue Typing- Only giving the kidney to patients who have the same blood group and antigens very similar to the donor kidney
            • Immuno-suppressant drugs: Must be taken by patient for the rest of their life
              • Unfortunately the drugs also suppress the immune system which can lead to infection
        • Advantages/ Dissadvantages
          • Patients can lead a more normal life without having to watch what they eat and drink
          • Cheaper for the NHS overall
          • Must take immune-suppressant drugs which increase the risk of infection
          • Shortage of organ donors
          • Kidney only lasts 8-9 years on average
          • The operation carries considerable risks


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