September 16, 2014

Physiologists find muscles may contain temperature sensors

Muscles could play an important role in the regulation of sweating and therefore body temperature, according to recent research from UOW.  

The research, published in the journal Acta Physiologica, found that muscles might do more than simply generate heat and create movement in the body.

Associate Professor Nigel Taylor, from the Centre of Human and Applied Physiology, who led the study, said like most motor vehicles, mammals are only about 20 per cent efficient, meaning that most of the energy used to perform muscular activity results in the accumulation of heat within the body.

"Just like in a car, the failure to remove this heat results in a problem,” Professor Taylor said.

“For humans, this is called hyperthermia, and it can have a wide range of consequences, some of which are lethal.”

Fortunately, natural selection has resulted in humans possessing an ability to dissipate this heat (sweating).

“This process is controlled by the central nervous system (anterior hypothalamus), and it relies upon the provision of sensory information that is provided by temperature sensors. These are located in various deep-body structures (brain, spinal cord, major blood vessels) and the skin,” Professor Taylor said.

However Professor Taylor’s team have found new evidence that these receptors may also be found within exercising muscle.

Co-author Dr Herb Groeller said: "Muscles may in fact have an ability to sense the heat that is produced during exercise. Muscles also appear to influence sweating. When sweat evaporates, the heat produced by the muscles is transferred to the environment, cooling the body. By having temperature sensors located close to the heat source, humans have more precise control of this evaporative cooling."

If correct, this research will not only increase our understanding of physiology, but it will provide another example of the efficiency of evolution, for the positioning of temperature sensors next to heat producing structures makes for a very effective way of preventing heat illness.

“Since our African ancestors were hunters who relied very heavily upon their endurance capabilities to catch larger and faster animals, then the presence of such sensors may well have given them an advantage over their prey, and one that has been passed to contemporary humans,” Professor Taylor said.