Regulating temperature

• Too hot


  1. Hairs lie flat.
  2. Sweating- A layer of liquid sweat made by sweat glands, carried up by sweat ducts and released by sweat pores onto the skin and evaporates removing heat energy.
  3. Vasodilation - Blood vessels in the skin widen so more heat from the blood is lost to the environment.
• Too cold


  1. Hairs stand on end to trap a layer of insulating air over skin reducing heat loss
  2. Shivering- Involuntary contraction of the muscles increases respiration and the release of heat energy.
  3. Vasoconstriction- Blood vessels in the skin get narrower so less heat is lost from the blood to the environment.
• Diagram of arm

  A) (Hair) Erector muscle

  B) Hair

  C) Sweat Pore

  D) Sweat Duct

  E) Sweat Gland

  F) Blood Capillaries

  
• Why is it important to control temperature?

  Body's temperature must remain at 37℃ and this is optimum temperature for enzymes to work best at
• The hypothalamus in the brain monitors changes in the blood's temperature (thermoregulatory centre) and the skin helps control these changes
• The control of body temperature is an example of negative feedback.
• Temperature increases above 37°C


  Vasodilation: Dilation of blood vessels near
• Temperature decreases below 37°C


  Vasoconstriction: Constriction of blood vessels