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The opposite condition, when body temperature decreases below normal levels, is known as hypothermia. It occurs when the body loses heat faster than producing it. The core temperature of the body normally remains steady at around 36.5–37.5 °C (97.7–99.5 °F).
Clinical hypothermia occurs when the core temperature drops below 35 °C (95 °F). [21] Heat loss is a major limitation to swimming or diving in cold water. [8] The reduction in finger dexterity due to pain or numbness decreases general safety and work capacity, which consequently increases the risk of other injuries.
Systematic tests have shown that the timing of thermal status is important. Body warmth, promoting high perfusion during ingassing, promotes high inert gas loading, which increases decompression risk. Body warmth during decompression, and the associated higher overall perfusion, promotes high rates of outgassing, and reduces decompression risk.
Sweating causes a decrease in core temperature through evaporative cooling at the skin surface. As high energy molecules evaporate from the skin, releasing energy absorbed from the body, the skin and superficial vessels decrease in temperature. Cooled venous blood then returns to the body's core and counteracts rising core temperatures.
A Lindbergh perfusion pump, c. 1935, an early device for simulating natural perfusion. Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, [1] usually referring to the delivery of blood to a capillary bed in tissue. Perfusion may also refer to fixation via perfusion, used in histological ...
Hence, if the body were perfectly insulated, core temperature would continue to increase until lethal core temperatures were achieved. Conversely, we are normally in surroundings that are considerably cooler than the body's core temperature of 37 °C (98.6 °F) creating a gradient for thermal energy flow from the core to the surroundings.
While most systems of the body show some degree of autoregulation, it is most clearly observed in the kidney, the heart, and the brain. [1] Perfusion of these organs is essential for life, and through autoregulation the body can divert blood (and thus, oxygen ) where it is most needed.
Ventilation–perfusion coupling is the relationship between ventilation and perfusion processes, which take place in the respiratory system and the cardiovascular system. [1] Ventilation is the movement of gas during breathing, and perfusion is the process of pulmonary blood circulation , which delivers oxygen to body tissues. [ 2 ]