Homeostasis - Body Temp

• All animals are classed as either ectotherms or endotherms, depending on how they control their body temperature.
• Ectotherms can't control their body temperature internally - they control their temperature by changing their behaviour.
• Endotherms control their body temperature internally by homeostasis. They can also control their temperature by behaviour.
• Ectotherms' internal temperature depends on the external temperature and they can manipulate it by changing their behaviour.
• Endotherms' internal temperature is less affected by the external temperature.
• Ecotherms' activity level depends on the external temperature - they're more active at higher temperatures and less active at lower temperatures.
• Endotherms' activity level is largely independent of the external temperature - they can be active at any temperature.
• Ectotherms have a variable metabolic rate and they generate very little heat themselves.
• Endotherms have a constantly high metabolic rate and they generate lots of heat from metabolic reactions.
• Sweating - more sweat is secreted from sweat glands when they body's too hot. The water in sweat evaporates from the surface of the skin and takes heat from the body. The skin is cooled.
• Mechanisms to REDUCE body temperature: Hairs lie flat, Sweating and Vasodilation.
• Hairs Lie Flat - The usual layer of hair that traps air providing insulation has eractor pili muscles which relax so less air can be trapped and heat can be lost more easily.