homeostasis basics

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  • Created by: Agata
  • Created on: 28-02-16 21:13
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  • Changes in your external environment can affect your internal environment - the blood and tissue fluid that surrounds your cells.
    • Homeostasis Basics
      • Temperature
        • If body temperature is too high (e.g. 40C) enzymes may become denatured. The enzyme's molecules vibrate too much, which breaks the hydrogen bonds that hold them in their 3D shape. The shape of the enzyme's active site is changed and no longer works as a catalyst. This means metabolic reactions are less efficient.
        • If body temperature is too low enzyme activity is reduced, slowing the rate of metabolic reactions.
        • The highest rate of enzyme activity happens at their optimum temperature (about 37 C in humans).
      • pH
        • If blood pH is too high or too low (highly alkaline or acidic) enzymes become denatured. The hydrogen bonds that hold them in their 3D shape are affected so the shape of enzyme active site is changed and it no longer works as a catalyst. This means metabolic reactions are less efficient.
      • Glucose
        • It's important to maintain the right concentration of glucose in the blood because cells need glucose for energy. Blood glucose concentration also affects the water potential of blood- this is the potential (likelihood) of water molecules to diffuse out of or into a solution.
          • If blood glucose concentration is too high the water potential of blood is reduced to a point where water molecules diffuse out of cells into the blood by osmosis. This can cause the cells to shrivel up and die.
          • If blood glucose concentration is too low, cells are unable to carry out normal activities because there isn't enough glucose for respiration to provide energy.
    • Homeostasis involves control systems that keep your internal environment roughly constant (within certain limits).
    • Keeping your internal environment constant is vital for cells to function normally and to stop them being damaged.
  • The highest rate of enzyme activity happens at their optimum pH- usually around pH 7 (neutral), but some enzymes work best at other pHs, e.g. enzymes found in the stomach work best at a low pH.

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