Responding to a fall in temperature

• • When temperature receptors detect that core body temperature is too low, they send impulses to the thermoregulatory centre, which processes the information and triggers the effectors to reduce the amount of heat lost from the body
• Negative feedback system:

  • Optimum body temperature
  • Fall in body temperature
  • Receptors detect change
  • Thermoregulatory centre receives and processes the information, then sends impulses to effectors
  • Effectors respond
• Responses that increase core body temperature:

  1. Hairs on the skin stand up

  • Traps an insulating layer of air next to the skin, reducing the amount of energy transferred to the environment
• 2. No sweat is produced
• 3. Blood vessels supplying skin capillaries constrict (get narrower) to reduce the skins blood supply

  • This is called vasoconstriction
  • Reduces the amount of blood that flows close to the skin and so less energy is transferred from the skin to the environment
• 4. When you're cold you shiver (your muscles contract immediately)

  • This needs respiration which transfers some energy to warm the body
• What is vasoconstriction?

  Vasoconstriction is the narrowing of blood vessels, resulting in a decrease in blood flow.