Thermoregulation as Negative Feedback Control
- Thermoregulation is the control of internal body temperature
- Thermoregulation is an example of a negative feedback mechanism; when body temperature deviates from pre-set limits, the responses of the body act to reverse the change and bring temperature back to normal
- Negative feedback is brought about by:
- Using receptors to detect any deviation from normal levels
- External body temperature is monitored using peripheral thermoreceptors in the skin
- Internal body temperature is monitored using receptors located inside the hypothalamus of the brain
- Effectors respond to any deviation from normal levels
- Controlling heat loss at the skin to the external environment
- Modifying the generation of heat inside the cells by metabolism
- Using receptors to detect any deviation from normal levels
Negative feedback mechanism diagram
Thermoregulation is an example of negative feedback; the 'factor' here is temperature, the 'stimulus' is a change in internal body temperature, and the 'corrective mechanisms' are the action of effectors that control heat generation and loss
- Examples of effectors involved with temperature change include:
- The hypothalamus
- Regulates secretion of a hormone called thyrotropin-releasing hormone
- Thyrotropin-releasing hormone stimulates the pituitary gland to release thyroid-stimulating hormone
- Thyroid-stimulation hormone stimulates the thyroid gland to release thyroxin
- Thyroxin increases metabolic rate
- Altering the level of thyroxin alters heat generation by cell metabolism, aiding regulation of body temperature
- Muscle tissue
- Shivering in the muscles raises the metabolic rate of muscle cells, releasing heat energy
- Adipose tissue
- White adipose tissue stores lipids in a layer beneath the skin and around the internal organs, providing insulation that aids temperature regulation
- Brown adipose tissue can generate heat energy before shivering begins in the muscles; this is known as non-shivering thermogenesis
- The hypothalamus