• 2011-05-01

    热舒适讲义02:人体如何调节体温 - [可持续]

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    人体如何调节体温 How is Body Temperature regulated?

    译者:童梦

    人体有一套非常有效的温度调节机制,确保核心体温维持在37℃左右。

    当身体感觉过热时,会启动两个过程。首先,毛细血管扩张,增加流
    经皮肤的血液,以助散热,若还无法降温,就会流汗。流汗是非常有
    效的冷却工具,因为汗液蒸发会带走大量热量。只要核心体温提高零
    点几度,流汗便开始了,从而将散热量提高三倍之多。

    当身体感觉过冷时,首先,毛细血管会收缩,流经皮肤血液减少,以
    减少热损失。接下来,人体会刺激肌肉运动产生热量,这一机制导致
    了寒颤。人体这套御寒系统也十分有效,能够产生可观热量以维持核
    心体温。

    调节体温的控制系统机制相当复杂,至今人类仍无法完全理解。然而,
    这套控制系统中,最重要的两个感应器已被发现,分别位于皮肤和下
    丘脑中。下丘脑感应器负责热感应,当核心体温超过37℃时,启动降
    温机制。皮肤感应器负责冷感应,当皮肤温度低于34℃时,启动御寒
    机制。

    有趣的是,如果冷热感应器同时向大脑发出信号,大脑会抑制其中一
    种或全部两种保护机制。

    Man has a very effective temperature regulatory system, which ensures that
    the body’s core temperature is kept at approximately 37°C.

    When the body becomes too warm, two processes are initiated: first the blood
    vessels vasodilate, increasing the blood flow through the skin and subsequently
    one begins to sweat. Sweating is an effective cooling tool, because the energy
    required for the sweat to evaporate is taken from the skin. Only a few tenths of
    a degrees increase in the core body temperature can stimulate a sweat production
    which quadruples the body’s heat loss.

    If the body is getting too cold, the first reaction is for the blood vessels to
    vasoconstrict, reducing the blood flow through the skin. The second reaction is
    to increase the internal heat production by stimulating the muscles, which causes
    shivering. This system is also very effective, and it can increase the body’s heat
    production dramatically.

    The control system which regulates the body temperature is complex, and is not
    yet fully understood. The two most important set of sensors for the control system
    are however known. They are located in the skin and in the hypothalamus. The
    hypothalamus-sensor is a heat sensor which starts the body’s cooling function
    when the body’s core temperature exceeds 37°C. The skin-sensors are cold
    sensors which start the body’s defence against cooling down when the skin
    temperature falls below 34°C.

    If the hot and cold sensors output signals at the same time, our brain will inhibit
    one or both of the body’s defence reactions.

    参考:www.blowtex-educair.it/DOWNLOADS/Thermal%20Comfort.htm

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    旋转菠萝刀 2009-05-01