Search results
Results from the WOW.Com Content Network
As in other mammals, human thermoregulation is an important aspect of homeostasis. In thermoregulation, body heat is generated mostly in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. [1] Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid.
Sweating occurs when the ambient air temperature is above 35 °C (95 °F) [dubious – discuss] and the body fails to return to the normal internal temperature. [18] The evaporation of the sweat helps cool the blood beneath the skin. It is limited by the amount of water available in the body, which can cause dehydration. [5]
Children younger than four years old and adults older than 65 are at a higher risk of serious heat illness due to impaired thermoregulation, even at rest, especially in hot and humid conditions without adequate cooling [20] Insufficient access to water, air conditioning, or other cooling methods [1]
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation.
Behavioral thermoregulation takes precedence over physiological thermoregulation since necessary changes can be affected more quickly and physiological thermoregulation is limited in its capacity to respond to extreme temperatures. [34] When the core temperature falls, the blood supply to the skin is reduced by intense vasoconstriction. [18]
There is a tradeoff between limiting gas flow through the insulating garment to minimise convective heat transfer and allowing easy venting of excess gas in the suit. A stable loft will allow adequate gas flow around the undergarments for rapid venting and equalisation, but maintain a fairly constant thickness of the undergarments for insulation.
In convective heat transfer, Newton's Law is followed for forced air or pumped fluid cooling, where the properties of the fluid do not vary strongly with temperature, but it is only approximately true for buoyancy-driven convection, where the velocity of the flow increases with temperature difference.
In temperate environments the blood flow to the skin is much higher than required for metabolism, the determining factor is the need for the body to get rid of its heat. In fact, skin can survive for long periods of time (hours) with sub-physiological blood flow and oxygenation, and, as long as this is followed by a period of good perfusion ...