homeostasis

• how does the nervous system impact thermoregulation (3)

  • the thermoregulatory system in the hypothalamus contains thermoreceptors which detect changes in tempreture of the blood
  • part of the CNS and is automatic (not autonomic)
• describe the characteristics of endotherms

  • generates heat from their metabolism
  • maintains a stable core temperature regardless of environmental change
  • can survive in a wide range of environments
• describe characteristics of endotherms

  • core body temperature is dependant on the environment
  • use behavioural adaptations to overcome this
• explain what the term homeostasis means (2)

  • keeping the bodies internal environment at a constant using negative feedback
  • within a narrow range even though the environments changing
• why are communication systems needed in multicellular organisms

  • to respond to internal and external stimuli
  • to coordinate the activities of different organs
• how would an endotherm detect temperature change (2)

  • peripheral receptors in the skin responding to external stimuli
  • receptors in the thermoregulatory centre in the hypothalamus detect change in blood temperature
• thermoregulation in endotherm when an increase in temperature (5)

  • heat loss centre in hypothalamus activated
  • send impulses through autonomic motor neurones to effectors in the muscles and skin
  • increased sweating , evaporation releases heat energy from the skin
  • vasodilation of arterioles results in increased heat loss by radiation
  • hair erector muscles relax to avoid trapping an insulating layer of air
• describe behavioural responses of ectotherms

  • orientating their body so the highest/lowest SA is exposed to the sun
  • conduction , by pressing their bodies against the ground
  • minimise/maximise movement
• why is a fever accompanied by uncontrollable shivering

  • because the new normal body temperature is higher therefore the body tries to increase it
• why does the body sweat when you have a fever

  • water has a high latent heat of evaporation
  • heat energy lost when sweat evaporates from the skin
  • cooling down the blood below the surface