homeostasis+exercise

• describe how thermoregulatory mechanisms are controlled to help marathon runners avoid heat stress(4)

  • thermoreceptors in skin detect an increase in heat, sends impulses to thermoregulatory centre in hypothalamus
  • hypothalamus sends impulses to sweat glands to increase sweating
  • also causes vasodialation of capillaries and constriction of shunt vessels-increases blood flow to surface of skin
  • decreases metabolic rate
• explain the role of the brain in reducing the students heart rate after exercise(3)

  • chemoreceptors detect a change in blood CO2 levels or PH
  • the cardiovascular control centre recieves impulses from chemoreceptors and sends impulses to the heart
  • thus impulses are transmitted along parasympathetic NS to SAN to reduced HR
• describe how the brain reduces the activity of sweat glands after the exercise(2)

  • thermoreceptors detect a decrease in temperature
  • thermoregulatory centre in the hypothalamus sends fewer impulses to sweat glands
• explain the role of the nervous system in bringing about the increase in temperature of the fingertip(5)

  • thermoreceptors in skin detect an increase in temperature
  • thermoregulatory centre in hypothalamus recieves impulse and co ordinates a response
  • thus more impulses sent along the sympathetic nerves
  • causing vasodialation of arterioles
  • so more warm blood flows near the skin surface