Thermoregulation - Anatomy & Physiology

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Thermoregulation

Thermoregulation is the ability of an endothermic organism to maintain a relatively constant body temperature despite fluctuations in temperature of the external environment. This is a vital part of homeostasis.

  • Homeotherm/Endotherm: an organism with an internal temperature which remains relatively constant despite external temperature fluctuations.
  • Poikilotherm/Ectotherm: an organism having a body temperature which fluctuates with the external environment - eg Fish, Reptile.

Mechanism of Action

The thermoregulatory mechanism consists of:

  1. Sensory Component: neurones that possess nerve endings with thermoreceptors continuously monitor body temperature and transmit it to the integrating centre. These neurons may be within the skin or internal organs.
  2. Integrating Centre: the Hypothalamus is the control centre in the brain which compares the temperature information with an Internal Reference or Set point.
  3. Motor Component: neurons which send signals to alter the internal temperature - altering heat production or heat loss.
  • These command signals may travel via the somatic motor system and affect heat production in skeletal muscle.
  • These command signals may travel via the Sympathetic Nerve Fibres and change
    • Blood Flow to the Skin
    • Sweat Gland Activity
    • Activity of the smooth muscles which regulate fur/plumage thickness