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  • Homoestasis part 2.
    • Control of body temperature
      • It is important to keep our body temperature at about 37 degrees Celsius. This is because it is the best temperature for enzymes to work.
      • When we feel too hot we need to lose heat faster as our core body temperature is at danger of rising. We do this by the following 2 ways.
        • Sweating
          • As water evaporates from our skin, it absorbs heat energy. This cools the skin and the body loses heat.
        • Vasodilation
          • Blood capillaries near the skin surface get wider to allow more blood to flow near the surface. Because the blood is warmer than the air, it cools down and the body loses more heat.
      • When we feel too cold we are in danger of losing heat too quickly and cooling down. This means we need to conserve our heat to maintain a constant 37 degrees. We can do this by;
        • Shivering is rapid contracion and relaxation of body muscles. This increases the rate of respiration and more energy is released as heat.
        • Sweating less
        • Vasoconstriction is when blood capilarries near the skin surface get narrower and this process reduces blood flow to the surface. The blood is diverted to deeper within the body where there is more heat.
      • Hypothermia occurs when blood temperature gets too low. It can be fatal.
    • Keeping cool during exercise.
    • Controlling body water
      • Too much water?
        • 1. Hypothalamus (part of the brain) detects too much water in blood.
          • 2. Pituitary gland releases less ADH
            • 3. Kidneys absorb more water from blood.
              • 4. More water reachers bladder and is lost through urine
                • 5. Blood water levels turns to normal.
      • Too little water?
        • 1. Hypothalamus detects too little water in blood.
          • 2. Pituitary gland releases more ADH
            • 3. Kidneys absorb less water from blood.
              • 4. Less water reaches bladder and is lost through urine.
                • 5. Blood water levels return to normal.


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