The epidermis is the surface layer of the skin. It protects the body from bacteria. It also stops the leakage of the plasma from the blood vessels that are spread in the dermis. In case of sudden loss of blood and plasma, the compensatory physiological mechanisms of the body fail. Shock follows as a result of a drop in the amount of blood reaching the chambers of the heart.
There are recipients of heat and cold that are spread in the dermis. The recipients of heat are at their peak when the temperature is between 32-48 centigrade. But, when temperature is 50 centigrade the recipients lose their sensitivity and in order to bring back the sense of feeling the skin should be replaced. This scientific fact mentioned in the Holy Qur’an 1400 years ago. God says:
Surely those who disbelieve in Our signs- We shall certainly roast them at a Fire, as often as their skins are wholly burned, We shall give them in exchange other skins, that they may taste the chastisement, surly God is All–Mighty, All–Wise
On the other hand man feels extreme pain when temperature reaches freezing point that is why God orders the fire in which Abraham was thrown to cool down and be safe, otherwise Abraham would have sensed extreme pain from cold as well as hot temperature
We said O fire, be coolness and safety for Abraham!