5.1.4 - temperature control in ENDOTHERMS

• what are endotherms?

  organisms that uses heat from metabolic reactions (internal sources) to maintain body temperature
• what responses do endotherms use to internally maintain body temps?

  • behavioural and physiological
• In humans, what part of the body detect changes and send them to the thermoregulatory centre in hypothalamus?

  • thermoreceptors in hypothalamus (core body)
  • skin(peripheral body - early signals )
• behavioural responses in endotherms if TOO HOT

  • Behaviour too Hot:
  • hide away from sun in the shade
  • remain inactive
  • orientate body to reduce SA exposed to sun
  • wet skin so evaporations transfer heat
• behavioural responses in endotherms if TOO COLD

  • Behaviour too Hot:
  • lie in the sun
  • move about generating heat in muscles
  • orientate body to increase SA exposed to sun
  • Remains dry
• physiological responses in endotherms if TOO HOT

  • if TOO HOT:
  • sweat released evaporates, transferring heat
  • hair flat ( erector pili muscles relaxed) to increase heat lose
  • vasodilation of arterioles increase blood through capillaries
  • panting, breathing heavily, increase in evaporation and heat transfer
  • less heat from respiration and muscle contraction (exergonic)
• 
  

  • no sweat made
  • hair erect ( erector pili muscles contract) to trap insulating air
  • vasoconstriction of arterioles diverts blood from skin surface
  • less panting
  • more heat from evaporation and shivering (exergonic)
• advantages of endotherms?

  • maintain constant body temperature
  • remain active, even if external temperature falls
  • can live in colder parts of planet
• disadvantages of endotherms?

  • lots of energy needed to regulate body temp
  • need more food and less used for growth