Controlling Body Temperature

• The body has to keep its insides at around 37°C - the optimum temperature for enzymes in the body
• The body has to balance the amount of energy gained (e.g. through respiration) and lost to keep the core body temperature constant
• There is a thermoregulatory centre in the brain, which contains receptors that are sensitive to the temperature of the blood flowing through the brain
• The thermoregulatory centre also receives impulses from temperature receptors in the skin, giving information about skin temperature
• Negative feedback system - Body warms up:

  1)Temperature receptors detect that core body temperature is too high

  2) The thermoregulatory centre acts as a coordination centre - it receives information from the temperature receptors and triggers the effectors automatically

  3) Effectors, e.g. sweat glands, produce a response and counteract the change
• Negative feedback system - Body cools down:

  1)Temperature receptors detect that core body temperature is too low

  2) The thermoregulatory centre acts as a coordination centre - it receives information from the temperature receptors and triggers the effectors automatically

  3) Effectors, e.g. muscles, produce a response and counteract the change
• Some effectors work antagonistically, e.g. one effector heats and another cools - they'll work at the same time to achieve a very precise temperature. This mechanism allows a more sensitive response
• Different responses are produced by effectors to counteract an increase or decrease in body temperature
• • Effectors include muscles and glands that produce a specific response to a detected stimulus
• When you're too hot:

  • Sweat is produced by sweat glands and evaporates from the skin. This transfers energy to the environment
  • The blood vessles supplying the skin dilate so more blood flows close to the surface of the skin. This is called vasodilation. This helps transfer energy from the skin to the environment

  
• When you're too cold:

  • Hairs stand up to trap an insulating layer of air
  • No sweat is produced
  • Blood vessles supplying skin capillaries constrict to close off the skin's blood supply. This is called vasoconstriction
  • When you're cold you shiver too (your muscles contract automatically). This needs respiration which transfers some energy to warm the body