The skin and temperature control

  • Created by: Harry
  • Created on: 17-05-14 18:31

The skin

General roles of the skin

  • Acts as a tough, outer layer to be able to resist mechanical damage
  • Acts as a barrier to the entry of disease-causing microorganisms
  • Acts as a sense organ for touch and temp. changes
  • Controls the loss of heat through the body's surface
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Temperature control (part 1)

Temperature control


  • Sweat glands produce greater amounts of sweat => is secreted to the surface of the skin
  • This liquid evaporates and turns into a gas => this change needs energy (aka. the latent heat of vaporisation)
  • When sweat evaporates, the energy is supplied by body heat => cools the body down
  • Only has a cooling action when it evaporates => in humid atmospheres, the sweat stays on the skin and doesn't evaporate


  • Lies flat against skin's surface => happens because of relaxation of muscles known as hair erector muscles
  • In cold conditions => muscles contract and hairs are pulled upright 
  • In warm conditions => muscles relax and hairs are left lying against skin's surface
  • Trap a layer of air next to the skin, and because air is a poor conductor of heat, it acts as an insulator
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Temperature control (part 2)

Blood vessels

  • There are tiny blood vessels called capillary loops in the dermis 
  • Blood flows through these loops, radiating heat to the outside, and cooling the body down
  • If body is too hot, small arteries leading to the capillary loops dilate => increases the blood flow to skin's surface => aka. Vasodilation
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