Biology Uint 3 GCSE Part 2

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  • Created by: A.B.
  • Created on: 22-04-13 19:48
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  • Kidney Transplants
    • In a kidney transplant, diseased or damaged kidneys are replaced with a healthy kidney from a donor.
      • The donor kidney is joined to the blood vessels in the groin of the patient.
      • One kidney can balance your blood chemistry and remove waste urea for a lifetime.
        • Transplanted organs only last for about 9 years.
      • Advantages (compared to dialysis): eat what you want, do not have to attend dialysis sessions.
      • Disadvantages (compared to dialysis): risk of rejection, take medicine every day, regular check-ups, finding donors (decreasing because cars are safer and medicine improving).
        • Scientists are working on xenotransplantation which produces genetically engineered pigs with organs that could be used for human transplants.
    • To try and prevent rejection of the donor kidney, the tissue types of the donor and the recipient are matched as closely as possible. Immunosuppressant drugs are also used.
      • The antigens (proteins on the cell surface) of the donor organ are different to those of the recipient.
        • Causes a risk that the antibodies of the immune system of the recipient will attack the antigens on the donor organ which would result in rejection and destruction of the donor kidney.
      • The tissue types are matched using blood groups.
      • Immunosuppresant drugs are improving meaning tissue types do not have to be as well matched.
        • Disadvantages: prevent patients from dealing effectively with infectious disease.
    • Keeping Internal Conditions Constant Continued
      • Controlling Body Temperature
        • Your body temperature is monitered and controlled by the thermoregulatory centre in your brain.
          • Contains receptors that are sensitive to temperature in the blood flowing through the brain itself.
          • Extra information comes from temp receptors in the skin which can detect a difference of as little as 0.5 degrees.
        • Your body temperature must be kept at the level at which enzymes work best.
          • Around 37 degrees.
        • Your body responds to cool you down or warm you up if your core body temperature changes.
          • Skin temperature can vary enormously without problems.
          • Things can affect internal body temperature.
            • Energy produced in muscles during exercise.
            • Fevers caused by disease.
            • The external temperature rising or falling.
        • The blood vessels that supply the capillaries in the skin dilate and constrict to control the blood flow to the surface.
        • Energy is released through evaporation of sweat from the surface of the skin to cool the body down.
          • If too hot, enzymes denature and can no longer catalyse reactions in your cells. To combat this more energy is released by blood vessels dilating which lets more energy escape by radiation and your rate of seating goes up.
        • Shivering involves contraction of the muscles that produces energy from respiration to warm the body.
          • If your body gets too cold, the rate of enzyme controlled reactions in your cells falls too low which means you dont release enough energy and cells begin to die. Conserve energy by blood vessels constrict which reduces energy lost at the surface of the skin. Sweat production is reduced and you shiver which needs lots of respiration which releases more energy.
          • Hair is also erect to trap a layer of air which is insulating.
      • Treatment and temperature issues
        • A kidney transplant allows someone to loive a normal life apart from taking immunosuppresant drugs. It costs less than dialysis in the long term.
          • Issues with dealing with kidney faliure.
            • People in developing countries sometimes sell their kidneys to earn the money they need.
            • Very expensive - 3% of NHS budget deals with kidney failure. It costs £30 800 for dialysis for one patient for one year.
        • Control of the body temperature in different conditions involves several different processes which cannot always cope in extreme conditions.
          • If your core body temperature drops to below 35% degrees you suffer from hypothermia. 30 000 people die each year.
            • Mainly affects very old and young.
          • Heat strokes can also kill.
            • Mainly affects very old and young.
      • Controlling Blood Glucose
        • Your blood glucose concentration is monitored and controlled by your pancreas.
          • When you digest a meal, large amounts of glucose pass into your blood. Without a control mechanism the levels would vary significantly. They would become so low at points that cells would not have enough to respire.
        • The pancreas produces the hormone insulin, which allows glucose to move from the blood into the cells.
          • When glucose levels increase, insulin is produced.
          • This also controls the storage of glycogen (insoluble glucose) which can be converted back to glucose when needed.
        • In type 1 diabetes, the blood glucose may rise to fatally high levels because the pancreas does not secrete enough insulin. It can be treated by injections of insulin before meals.
          • Cause thirst and lots of urine (as the glucose would go into the urine) as well as tiredness as the glucose would not enter the cells and instead fat and protein would be broken down to use as fuel which would cause weight loss.
          • To combat this, insulin is given as an injection. It is not given orally as it is a protein so would be digested in the stomach.
        • Glucagon allows glycogen to be converted back into glucose and released into the blood.
          • When your blood glucose concentration falls below the ideal range, the pancreas secretes glucagon which makes your liver break down glycogen, converting it back into glucose.
        • Glucose = a sugar found in the blood. Glycogen = a storage carbohydrate found in the liver and muscles. Glucagon = a hormone.
      • Treating diabetes
        • A variety of different methods are being used or developed to treat diabetes using genetic engineering and stem cell techniques.
          • Insulin used to come from animals however now genetic engineering can be used to develop bacteria that can produce pure human insulin.
          • Pancreas transplants but not enough donors and exchange insulin for immunosuppresant.
          • Transplanting the pancreatic cells that make insulin from both dead and living donors has only had limited success.
          • Produced insulin-secreting cells from embryonic stem cells.
        • Type 2 diabetes is treated by careful attention to diet and taking more exercise alone. If this doesn't work, drugs may be needed.
          • If this doesn't work there are drugs that:
            • help insulin work better on the body cells.
            • Help your pancreas make more insulin.
            • Reduce the amount of glucose you absorb in your gut.

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