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I read in "Essentials of Pathophysiology: Concepts of Altered Health States By Carol Porth" that

"The thermal pain receptors are stimulated only by extremes of temperature such as "freezing cold" below 5°C and "burning hot" above 45°C."

Also in "The Journal of Neuroscience, April 7, 2010 • 30(14):4933– 4942 • 4933" it states:

"In lightly anesthetized rats, hindpaw cooling with ethyl chloride, but not acetone, was sufficiently noxious to evoke withdrawal reflexes"

We know, 'burning-hot'-receptors induce a withdrawal reflex when we touch a very hot object, say hot frying pan.

But does this mean if we touch a very cold object (temperatures below 5°C), the 'freezing-cold'-receptors would induce a withdrawal reflex in humans?

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The withdrawal reflex is a nociceptive flexor reflex and is a spinal reflex intended to protect the body from damaging stimuli.

In other words, activation of heat receptors is not the trigger of the withdrawal reflex, it is the activation of pain receptors at high, tissue-damaging temperatures.

Extreme cold is also damaging and causes skin lesions akin to heat-induced burn wounds. Again, at a certain tipping point extremeley low temperatures become damaging, and cause frost bites (Sachs et al., 2015). At this point tissue damage will activate pain receptors and these cause the withdrawal reflex to be initiated.

Reference
- Sachs et al., Dtsch Arztebl Intv; 112(44): 741–7

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  • $\begingroup$ How cold does it have to be to cause harm? to cause withdrawal? $\endgroup$ – Display Name Mar 29 '17 at 12:47
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    $\begingroup$ @DisplayName - I deliberately left that out as it depends on the duration of the exposure. It's hard to say. $\endgroup$ – AliceD♦ Mar 29 '17 at 12:55

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