Homeostasis

• Homeostasis is maintaining a 'constant' internal environment
• Things that must be maintained

  • Body temperature
  • Water content
  • Blood glucose concentration
• When you are too hot...

  • Erector muscles relax = hairs lie flat
  • Lots of sweat (water + salt), transferring energy from your skin to the environment
  • Vasodilation - Blood vessels closer to the skin dilate = more blood flow nearer the surface = heat transfers to surrounding
• When you are too cold...

  • Erector muscles contract = hairs stand on end to trap an insulating layer
  • Very little sweat produced
  • Vasoconstriction - Blood vessels near the skin constrict, reducing blood flow near the surface = reduces heat lost to surroundings
  • Shivering
• Insulin and Glucagon control blood sugar level
• If blood glucose level is too high...

  1. Insulin secreted by pancreas
  2. Glucose moves from blood into liver and muscle cells
  3. Insulin converts glucose into glycogen
  4. Blood glucose reduced
• If blood glucose level is too low...

  1. Glucagon secreted by pancreas
  2. Glucagon converts Glycogen into Glucose in liver
  3. Glucose released by liver into blood
  4. Blood glucose levels increase
• Having diabetes means you can not control your blood sugar level

  • Type 1 = pancreas does not produce enough insulin
  • Type 2 = person becomes resistant to insulin
• Type 1 diabetes

  • Insulin injections
  • Regular exercise
  • Less sugar eaten
• Type 2 diabetes

  • Healthy diet
  • Exercise regularly
  • Lose weight