thermoregulation

• the optimum temperature of enzymes in the human body is 37 degrees Celsius if below enzyme activity slows down and if above enzymes denature
• the hypothalamus in the brain is the the thermoregulation centre. in contains receptors which are sensitive to blood temperature. receive impulses from receptors in the epidermis and dermis of the skin about the external temperature
• when the hypothalamus detects change it causes a response in the skin
• if temperature is above 37 it is detected by the hypothalamus:

  • the erector muscles relax so hair lies flat against the skin.
  • sweat is produced by sweat glands and released on the surface of the skin to cause a cooling effect as it evaporates and transfers energy to the environment
  • blood vessels close to the skin's surface dilate (vasodilation) so more blood flows near the surface and energy is transferred to surroundings
• if too cold temperature is detected by the hypothalamus.

  • erector muscles contract so hairs stand to trap an insulating layer of air.
  • little sweat is produced.
  • blood vessels near the skin's surface constrict (vasoconstriction), reducing blood flow near the surface, reducing energy transferred to surroundings.
  • shivering occurs as muscles contract and relax quickly which increases the rate of respiration and more energy is transferred to warm the body.