Control of Body Temperature

HideShow resource information
View mindmap
  • Control of Body Temperature
    • Temperature Control in Ectotherms and Endotherms
      • Ectotherms can't control their body temperature internally- they control their temperature by changing their behaviour.
        • This means the internal temperature of ectotherms depends on the external temperature.
          • Ectotherms have variable metabolic rate because they can't keep their internal temperature constant.
            • They generate very little heat themselves, this means the activity level of ectotherms depends on the external temperature too- more active at higher temps.
      • Endotherms control their body temperature internally by homeostasis, as well as altering their behaviour.
        • This means that, compared to ectotherms, the internal temperature of endotherms is less affected by the external temperature.
          • Endotherms have a constantly high metabolic rate because they can keep their internal temperature constant.
            • They generate a lot of heat from metabolic reactions. This means the activity levels of endotherms is largely independent of the external temperature.
    • Mechanisms to reduce body temperature
      • Reducing:      SWEATING- more sweat is secreted from sweat glands when the body's too hot. The water in sweat evaporates from the surface of the skin an takes heat from the body. The skin is cooled.
      • HAIRS LIE FLAT- mammals have a layer of hair that provides insulation by trapping air. When its hot, erector pili muscles relax so the hairs lie flat. Less air is trapped, so the skin is less insulated and heat can be lost more easily.
      • VASOLIDATION- when it's hot aterioles near the surface of the skin dilate. More blood flows through the capillaries in the surface layers of the dermis. This means more heat is lost from the skin by radiation and temperature is lowered.
    • Mechanisms to increase body temperature
      • SHIVERING- when it's cold, muscles contract in spasms. This makes the body shiver and more heat is produced from increased respiration.
      • HORMONES- the body releases adrenaline and thyroxine. These increase metabolism and so more heat is produced.
      • MUCH LESS SWEAT- less sweat is secreted from sweat glands when it's cold, reducing the amount of heat loss.
      • HAIRS STAND UP- erector pili muscles contract when it's cold, which makes the hairs stand up. This straps more air and so prevents heat loss.
      • VACOCONSTRICTION- when it's cold, aterioles near the surface of the skin constrict so less blood flows through the capillaries in the surface layers of the dermis. This reduces heat.
    • Control of body temperature by the hypothalamus
      • Body temperature in mammals is maintained at a constant level by a part of the brain called the hypothalamus. The hypothalamus receives information about both internal and external temperature from thermoreceptors
        • Thermoreceptors in the hypothalamus detect internal temperature.
        • Thermoreceptors in the skin (peripheral temperature receptors) detect external temperature.
        • Thermoreceptors send impulses along sensory neurones to the hypothalamus, which sends impulses along motor neurones to effectors. The effectors respond to restore the body temperature back to normal.
      • Rise in body temperature
        • When thermoreceptors detect body temperature is too high, they send impulses to the hypothalamus, which sends impulses to effectors. Effectors respond to increase heat loss from the body and to reduce the amount of heat that's produced by the body.
        • Fall in body temperature
          • When thermoreceptors detect body temperature is too low, they send impulses to the hypothalamus, which sends impulses to effectors. Effectors respond to produce more heat and to conserve it.

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Communication and Homeostasis resources »