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Mammals are endothermic homeotherms, which is a very precise way of saying they regulate their own body temperature. It is worth noting that not all organisms do so, because it would in fact be disadvantageous for some to do so. Furthermore some organisms regulate their body temperature solely through behavioural methods.

The different ways in which organisms can respond can be defined using the following terms.

  • homeotherms - control body temperature
  • poikilotherms - body at ambient temperature
  • endotherm - gains heat from internal activity
  • ectotherm - gains heat from external sources

The regulation of temperature in humans is actually the regulation of the core temperature. This explains why it is possible to get frostbite in the fingers or toes, yet still maintain the brain at 37oC.

Figure 2 : The regulation of core temperature in humans
The regulation of core temperature in humans

Table 1 shows the components of temperature regulation in humans

Table 1 : The components of temperature regulation in humans
Table 7 : The components of temperature regulation in humans

The following flow chart shows how the process of temperature regulation is a homeostatic process.

Figure 3 : The process of temperature regulation
The process of temperature regulation

In humans there are a variety of effectors that act in concert to maintain, or reduce, the core temperature. Many of these effectors are found in the skin. The action of the effectors found in the skin are shown in the tables 2 & 3, supported by figures 4 & 5, below

Figure 4 : The structure of human skin
The structure of human skin

Figure 5 : Temperature regulation in humans
The regulation of temperature in humans

Effectors in the skin responding to an elevated core temperature.

Table 2 : Effectors in the skin responding to an elevated core temperature
Table 8 : Effectors in the skin responding to an elevated core temperature

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Effectors in the skin responding to a depressed core temperature.

Table 3 : Effectors in the skin responding to a depressed core temperature
Table 9 : Effectors in the skin responding to a depressed core temperature

Another well-known response to a lowered core temperature is shivering. The effectors for this response are the body's skeletal muscles which contract and relax involuntarily to generate heat. A lowered core temperature also stimulates the release of the hormones adrenaline and thyroxine from the adrenal and thyroid glands. Both these hormones increase the body's metabolic rate again generating heat.  Exam Advice



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