Allah (Glory is to him) says:
"Those who reject our signs, we shall soon cast in to the fire, as often as their skins are roasted through, we shall change them for fresh skins, that they may taste the penalty for Allah is Exalted in power, wise" Al- Nesa'a chapter, verse:56
The above verse illustrates why Allah changes the unbelievers burnt skin by another to feel the most torment during their existence in the hell… so what is the secrete of this.
The microscopical anatomy illustrates to us that the skin is an organ rich with the nerve fibers that receive & transform all types of sensation from the external surrounding & either by free nerve ending & all these ends exist in all skin levels: epidermis (outer skin), dermis, the hypodermis tissues & it transforms the pain sensation, heat, pressure, coldness & touch sensation & there are nerve endings which have secretory function & regulate the skin glands blood vessels whether is more sensory by the receptors of pressure but it is less sensory by pain, heat & touch receptors with a big grade & thus when any person is injected by syringe so he feels maximum pain when it penetrates the skin & when it passed to the other tissues the pain sensation decreases.
And the skin when exposed to burn it leads to a great pain sensation because the fire warn the pain receptors which is the free nerve ending & also it warns the thermoreptors & which is corpuscles that is existed in the dermis & hypodermis which is called Ruffini Corpuscles & burning pain is maximum when the burn reaches the hypodermis tissue & called the third degree burn & if the burn extends to the under skin tissue the pain will decrease because these tissues are less sensitive for pain as it mentioned before & thus the kor'anic verse refers to the organ which is richest with the pain receptors is the skin as the burns are the most warning pain .
Allah (glory is to him) says: "Those who reject our signs we shall soon cast in to the fire, as often as their skins are roasted through, we shall change them for fresh skins, that they may taste the penalty for Allah is Exalted in power, wise"
Al- Nesa'a chapter, verse:56
Allah (Glory is to him) says:"(Here is) a parable of the Garden which the righteous are promised: in it are rivers of water incorruptible; rivers of milk of which the taste never changes; rivers of wise, a joy to those who drink, and rivers of honey pure and clear. In it there are for them all kinds of fruits; and grace from their Lord. (can those in such Bliss) be compared to such as shall dwell forever in the fire and be given , to drink, boiling water, so that it cuts up their bowels (to pieces)"
Mohammad chapter verse no:15
(cutting their intestines): Here Allah didn't say exchange it but said cut it because the intestine is free of the sensory nerve cells, so if we put a scope inside the digestive system the human won't feel any pain, only the pharynx pain during the entry of the scope & we take a part & the patient doesn't feel any pain so when the patient will feel the pain?
The patient feels the pain when he has a perforation in his intestines as the perforating ulcer so Allah said (cut) & we must be attentive to this accurate fluent expression as Allah said the expression (exchange) with skin and said the expression (cut) with intestines because the intestines are free of sensation and also free of nerve cells which is found in the peritoneal membrane, so when a perforation happens in the intestines a serve pain happens and thus the patient who is injured by a perforation in the digestive system will be suffering from a serve pain and his stomach becomes in a state called Board like Rigidity as board that is an emergency surgical case and an operation must be done to the patient immediately because the intestinal contents exit to the peritoneum which has the nerve ending and the sensation so he feels by a great pain so his stomach strained.
And there is another hint which relates to this subject that the human when he sometimes exposes to a disturbing view or pain he lost his conscious as a mean of defense for himself, that Allah (the Great & Almighty ) said about the unbelievers until he torments them :"But those who reject (Allah), for them will be the fire of Hell : no term shall be determined for them, so they should die, nor shall its penalty be lightened for them. Thus do we reward every ungrateful one! "
So they will be in a state they will neither be alive nor dead.